Injection mold design system and injection mold design method

ABSTRACT

An injection mold design method for correcting a profile of a product to be fabricated into a releasable profile from a mold to design an injection mold based on a corrected product shape, utilizing a storage device for storing information of the product shape and mold profile, a display device for displaying the product shape or the mold profile on a screen based on the information read from the storage device, an input device for inputting designation information necessary for correction of the product shape or the mold profile, and a controlling device for unloading information of lines or planes being obstructive to correction of the product shape and the mold profile in the storage device in response to the designation information input by the input device. The method comprises removing lines or planes from the screen, and replotting the lines or the planes on the screen in terms of the information of lines or planes unloaded into the storage device after the correction operation of the product shape of the mold profile is completed.

This is a divisional of U.S. application Ser. No. 09/569,265, filed May11, 2000, now U.S. Pat. No. 6,327,553 issued on Dec. 4, 2001, which is adivisional of U.S. application Ser. No. 09/084,965, filed May 27, 1998,now U.S. Pat. No. 6,192,327 issued on Feb. 20, 2001, which is adivisional of U.S. application Ser. No. 08/614,055, filed Mar. 12, 1996,now U.S. Pat. No. 5,812,402 issued on Sep. 22, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an injection mold design system and aninjection mold design method and, more particularly, a design supportsystem for a mold used for fabricating resin (plastics) injectingmoldings and a design method for designing the mold.

2. Description of the Related Art

In recent years, according to demands for more variety of productdesign, users' various usages etc., plastics have been widely used asmaterial of enclosures for electrical products since they may present anattractive appearance and may be molded arbitrarily. In addition, itentails such advantages that reduction in the number of parts andsimplification of assembly may be attained. This is because seats,bosses (projections), etc., these being used for mounting printedcircuit boards and other parts, and reinforcing members such as ribs maybe formed integrally with the enclosures if the enclosures arefabricated by resin injection molding.

FIG. 1A shows an example of moldings (molded products) formed by resininjection molding. In FIG. 1A, a reference 1 denotes a molding used asan enclosure of a portable electronic device, and a reference 2 denotesa bore portion provided in the molding 1. After preparing the mold inwhich a cavity having the same profile as that of the product is inadvance formed, melted resin is filled into the cavity and then cured,so that the molding 1 with a shape shown in FIG. 1A may be formed. Atthis time, the bore portion 2 may be formed by nests arranged in themold.

FIG. 1B shows a configuration of the mold. In FIG. 1B, a reference 3denotes a cavity (female mold) for defining an outer shape of themolding 1, and a reference 4 denotes a core (male mold) for defining aninner shape of the molding 1. When the cavity 3 is put on the core 4,the cavity corresponding to the products profile to be formed may beformed between them.

FIG. 1C shows a configuration of an injection molding machine on whichthe mold is mounted. With being arranged so as to oppose to each otherin the vertical direction, the cavity 3 and the core 4 are clamped on acavity plate 3A and a core plate 4A respectively. The cavity plate 3Amay be driven by a driving apparatus (not shown) to move in the verticaldirection. A reference 5 denotes a runner stripper plate in which arunner (not shown) is formed to introduce the resin 7 into the space inthe mold. The runner stripper plate 5 may be placed on the cavity plate3A. When the molds are opened, the runner stripper plate 5 may then beseparated from the cavity plate 3A to enable the resin cured in therunner to be removed from the runner. A reference 6 denotes a gate(pouring gate) formed in the mold. Resin 7 is filled into the cavity inthe mold via the gate 6.

A reference 8 denotes a gas vent (breathing hole) which is provided inthe mold to exhaust the air from the space in the mold to the exteriorwhen the resin is poured into the space in the mold. A reference 9denotes a cooling water path provided in the mold. Since the resin to befilled into the mold is heated at a temperature of a few hundreds ° C.,a temperature of the mold is raised when the resin is filled into themold. As a result, drawbacks such as not only reduction in moldingefficiency but also warpage, twist, etc. of the product are caused. Inorder to prevent the drawbacks, the mold is cooled by flowing waterthrough the cooling water path 9. Usually, the cooling water path 9 isprovided on the core 4 side.

A reference 10 denotes an extruder portion for extruding the moldings 1from the core 4. The extruder portion 10 has a rod-like member referredto as an ejector pin. The moldings 1 can be extruded from the core 4 byinserting the ejector pin into a through hole provided in the core 4.

In any event, since the injection mold is composed of the cavity 3 andthe core 4, as mentioned above, the mold must be split into the cavity 3side and the core 4 side when designing the mold. The split plane iscalled a parting plane. In case there is caused an undercut portion inthe products to be fabricated, the moldings cannot be stripped off fromthe mold if the parting plane is set incorrectly. Here the undercutportion may be defined as a portion serving as an engagement formed inthe mold opening direction when the product is taken out from the molds.If the undercut portion exists, consideration for providing a slidestructure to the mold or the like should be taken inevitably.

In order to strip the product off from the mold readily, slight slopes(draft slopes) are provided on the surface of the mold so as to preventinner surfaces of the mold from being formed perpendicularly to theparting plane. In the prior art, in the case of the mold having arelatively simple profile, mold designers be able to design the moldaccording to drawings prepared for the product while considering partingplane, draft slope, etc. Conversely, as for the product which must bedesigned by use of a plenty of free-form surfaces to achieve the highdesign property, it would become difficult to illustrate the profile ofthe product in the drawings. As a countermeasure to this drawback, firstthe product model (model) is formed, then profile lines of the productmodel are illustrated with many dots, and then the profile of theproduct is converted into numeric data by correlating these dots witheach other in terms of digitizing process. Then NC (Numeric Control)data used for cutting process and electric discharge machiningelectrodes are then prepared for based on the numeric data. According tothese data, the mold may be then fabricated by the electric dischargemachining electrodes.

In the meanwhile, there are some cases where the mold may be designed bymeans of the three dimensional CAD (Computer-Aided Design) system. Insuch cases, data of the product shape are first input into the CADsystem, then the product shape or the mold block (i.e., virtual blockdisplayed on the screen for illustrating an outer shape of the mold) inwhich a cavity corresponding to the product shape is formed is depictedon the display. While monitoring the screen of the display, the designermay draw the parting line on the screen to form the parting plane orselect the planes to which a draft slope is provided. The CAD system maythus output numeric data to form the mold in compliance with thesesetting conditions.

However, in the method where the designer has to design the mold on thebasis of the design drawings, the designer must design the mold whileconsidering undercut, draft slope, etc. as mentioned above. Therefore,it can be seen that, in the case of the product with complicate profile,it would become difficult for the designer to determine a solid productshape from the drawings. For this reason, according to this method,problems have been arisen that man-hour in design is increased anddesign error is prone to generate. Alternatively, in the method wheredata used for fabricating the mold are generated from the product model,there are some problems that, since the product model must be formed tohave a precise profile, the designer must be well practiced in formingthe product model and much time must also be consumed to form theproduct model.

Moreover, in the method where the three dimensional CAD system is used,the troublesome procedures would be required and further a great deal ofskill would be required for the designer since the mold designer mustdesign parting plane, draft slopes, etc. on the basis of image displayedon the screen of the display. Because of the causes such as missing ofthe undercut portion, the mold designer is apt to generate errors indesign.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a design systemcapable of designing an injection mold readily and in short time and adesign method employed in the same.

According to the injection mold design system of the present invention,in case the product shape or the mold profile should be corrected, sincelines or planes being obstructive to profile correction can be unloadedto a storing device temporarily, the designer may correct the productshape or the mold profile while monitoring the display screen on whichonly lines or planes indispensable to the certain profile correction aredepicted. Therefore, with displaying a stereoscopic drawing and aprojection drawing of the product on the display device, the designermay execute correction of shrinkage rate, extraction of parting line,provision of draft slope, etc. in an interactive manner.

According to the injection mold design method of the present invention,design items can be reduced by preparing parameters of the mold partsand fixing parts as patternized information, and in addition correction,change, etc. of the product shape and the mold profile can be effectedautomatically. Consequently, man-hour of design in typical designoperations can be significantly reduced.

According to the injection mold design method of the present invention,features of the mold which being indispensable to formation of the moldcan be grasped by extracting candidates of split borderlines of themold. In addition, lack of knowledge and experience as to the molddesign can be made up for by utilizing a loop check function for thesplit borderlines and a nest split function. Thus, the design method ofthe present invention enables the designer having little experience toexecute the mold design.

With the above, the present invention may extremely contribute to themold design support system capable of executing correction of theproduct shape, design of the mold, and design of manufacturing jigs inan interactive manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view illustrating an example of a moldingsaccording to the conventional injection mold design method;

FIG. 1B is a side view showing molds used for forming the example of themoldings in FIG. 1A;

FIG. 1C is a side view showing an injection molding machine on which themolds shown in FIG. 1B are mounted;

FIG. 2 is a view showing a configuration of an injection mold designsystem according to embodiments of the present invention;

FIGS. 3A to 3G are views illustrating various display functions of adisplay device according to embodiments of the present invention;

FIGS. 4A to 4C are flowcharts, when taken together, illustratinginjection mold design according to embodiments of the present invention;

FIG. 5 is a perspective view showing a cavity and a core in a coupledstate according to embodiments of the present invention;

FIG. 6 is a perspective view showing the cavity and the core in aseparated state according to embodiments of the present invention;

FIGS. 7A to 7C are enlarged partial sectional views showing the moldswhen designing a parting plane according to embodiments of the presentinvention;

FIGS. 8A and 8B are perspective views respectively showing split of anest portion according to embodiments of the present invention;

FIG. 9A is a perspective view showing split of the nest portionaccording to embodiments of the present invention;

FIG. 9B is a side view showing the nest portion in FIG. 9A;

FIG. 9C is a plan view showing the nest portion in FIG. 9A;

FIG. 10 is a flowchart illustrating profile detection of an outermostperiphery and through holes of a product shape according to a firstembodiment of the present invention;

FIG. 11 is a perspective view showing the product shape when detectingthe outermost periphery according to the first embodiment of the presentinvention;

FIG. 12 is a flowchart illustrating draft-sloped plane detectionaccording to a second embodiment of the present invention;

FIG. 13 is a flowchart illustrating assignment of priority level to thedraft-sloped plane according to a third embodiment of the presentinvention;

FIGS. 14A and 14B are perspective views showing the product shape beforeand after magnification when assigning the priority level according tothe third embodiment of the present invention;

FIGS. 15A to 15C are views respectively explaining shrinkage of theproduct shape when assigning the priority level according to the thirdembodiment of the present invention;

FIG. 16 is a flowchart illustrating provision of draft slope accordingto a fourth embodiment of the present invention;

FIGS. 17A and 17B are perspective views showing circular cone whenproviding the draft slope according to the fourth embodiment of thepresent invention;

FIG. 18 is an enlarged perspective view showing projection of a partingline when providing the draft slope according to the fourth embodimentof the present invention;

FIG. 19 is a perspective view showing the product shape havingdraft-sloped plane according to the fourth embodiment of the presentinvention;

FIG. 20 is a flowchart illustrating formation of the parting lineaccording to a fifth embodiment of the present invention;

FIGS. 21A and 21B are perspective views showing a circular cylinder whenforming the parting line according to a fifth embodiment of the presentinvention;

FIG. 22 is a plan view showing the product shape when forming theparting line according to the fifth embodiment of the present invention;

FIG. 23 is a flowchart illustrating loop check of the parting lineaccording to a sixth embodiment of the present invention;

FIGS. 24A and 24B are perspective views showing line elements whenchecking the parting line according to the sixth embodiment of thepresent invention;

FIG. 25 is a flowchart illustrating detection of undercut according to aseventh embodiment of the present invention;

FIG. 26 is a perspective view showing an opening portion when detectingthe undercut according to the seventh embodiment of the presentinvention;

FIG. 27 is a perspective view showing detection of opening portionsother than the undercut according to the seventh embodiment of thepresent invention;

FIGS. 28A and 28B are flowcharts, when taken together, illustratingcheck process of releasability of the product shape according to aneighth embodiment of the present invention;

FIGS. 29A to 29C are flowcharts, when taken together, illustratingformation process of the parting plane according to a ninth embodimentof the present invention;

FIGS. 30A to 30C are perspective views respectively showing split of themold into the cavity and the core according to the ninth embodiment ofthe present invention;

FIGS. 31A to 31C are flowcharts, when taken together, illustratingdetection process of a depth of the core and split candidate location ofthe core according to a tenth embodiment of the present invention;

FIG. 32 is a side view showing the cavity and the core when designingsplit nest of the mold according to the tenth embodiment of the presentinvention;

FIG. 33 is a flowchart illustrating assignment of priority level tosplit line candidates of the core according to an eleventh embodiment ofthe present invention;

FIG. 34 is a side view showing the cavity and the core when assigningthe priority level according to the eleventh embodiment of the presentinvention;

FIGS. 35A and 35B are flowcharts, when taken together, illustratingarrangement of mold base according to a twelfth embodiment of thepresent invention;

FIG. 36 is a fragmental sectional view showing a fixing structure of themold parts according to the twelfth embodiment of the present invention;

FIGS. 37A and 37B are perspective view showing a fixing structure of themold parts according to the twelfth embodiment of the present invention;

FIG. 38 is a view showing an image on the display device when designinga gate structure according to a thirteenth embodiment of the presentinvention;

FIG. 39 is a flowchart illustrating gate design according to thethirteenth embodiment of the present invention;

FIG. 40 is a perspective view showing the gate structure according tothe thirteenth embodiment of the present invention;

FIG. 41A is a perspective view showing the gate structure according tothe thirteenth embodiment of the present invention;

FIGS. 41B to 41D are sectional views showing an ejector pin according toa sixteenth embodiment of the present invention;

FIG. 42 is a view showing an image on the display device when designingthe gate structure according to a thirteenth embodiment of the presentinvention;

FIG. 43 is a view showing an image on the display device when designinga runner structure according to a fourteenth embodiment of the presentinvention;

FIG. 44 is a flowchart illustrating runner design according to thefourteenth embodiment of the present invention;

FIG. 45 is a perspective view showing the runner structure according tothe fourteenth embodiment of the present invention;

FIGS. 46A to 46D are sectional views showing the runner structureaccording to the fourteenth embodiment of the present invention;

FIG. 47 is a flowchart illustrating gas vent design according to afifteenth embodiment of the present invention;

FIG. 48 is a plan view showing the core when designing the gas ventstructure according to the fifteenth embodiment of the presentinvention;

FIGS. 49A to 49C are views showing images on the display device obtainedby superposing a plan view of the core and resin superplasticizedanalysis chart when designing the gas vent structure according to thefifteenth embodiment of the present invention;

FIG. 50 is a view showing an image on the display device when designingthe ejector pin according to a sixteenth embodiment of the presentinvention;

FIG. 51 is a view showing another image on the display device whendesigning the ejector pin according to a sixteenth embodiment of thepresent invention;

FIG. 52 is a flowchart illustrating ejector pin design according to thesixteenth embodiment of the present invention;

FIG. 53 is a perspective view showing the ejector pin in connection withthe product shape according to the sixteenth embodiment of the presentinvention;

FIG. 54 is a view showing an image on the display device when designinga cooling path according to a seventeenth embodiment of the presentinvention;

FIG. 55 is an isometric drawing showing the mold when designing thecooling path according to the seventeenth embodiment of the presentinvention;

FIGS. 56A and 56B are segmental side views showing the mold whendesigning a link structure according to an eighteenth embodiment of thepresent invention;

FIG. 57 is a view explaining dimensional tolerance according to anineteenth embodiment of the present invention;

FIG. 58 is a view illustrating a menu system of the mold design systemaccording to a twentieth embodiment of the present invention;

FIGS. 59A and 59B are views respectively illustrating another menusystem of the mold design system according to the twentieth embodimentof the present invention;

FIG. 60 is a view illustrating use segments of mold design itemsaccording to the twentieth embodiment of the present invention;

FIG. 61 is a flowchart illustrating detection of the undercut in theproduct shape according to the twenty-first embodiment of the presentinvention;

FIGS. 62A to 62C are views showing the product shape with the undercutaccording to the twenty-first embodiment of the present invention;

FIGS. 63A and 63B are views showing the product shape without theundercut according to the twenty-first embodiment of the presentinvention;

FIG. 64 is a flowchart illustrating extraction process of the partingline according to a twenty-second embodiment of the present invention;

FIG. 65A is a perspective view showing the product shape according tothe twenty-second embodiment of the present invention;

FIG. 65B is a view showing the product shape viewed from the moldopening direction according to the twenty-second embodiment of thepresent invention;

FIGS. 66A to 66D are views illustrating displayed examples on thedisplay device when extracting the parting line according to thetwenty-second embodiment of the present invention;

FIGS. 67A and 67B are flowcharts, when taken together, illustratingformation process of the parting plane according to a twenty-thirdembodiment of the present invention;

FIGS. 68A to 68E are views showing the parting line and plane elementswhen forming the parting plane according to the twenty-third embodimentof the present invention;

FIG. 69 is a flowchart illustrating design process of the ejector pinaccording to a twenty-fourth embodiment of the present invention;

FIGS. 70A to 70D are views showing screen images on the display devicewhen designing the ejector pin according to the twenty-fourth embodimentof the present invention;

FIG. 71 is a flowchart illustrating design process of the mold baseaccording to a twenty-fifth embodiment of the present invention;

FIG. 72 is a view illustrating screen images on the display device whendesigning the mold base according to the twenty-fifth embodiment of thepresent invention;

FIG. 73 is a view showing a menu screen for the injection moldingmachine when designing the mold base according to the twenty-fifthembodiment of the present invention;

FIG. 74 is a flowchart illustrating usage of configuration fileaccording to a twenty-sixth embodiment of the present invention;

FIG. 75 is a view illustrating the contents of the configuration fileaccording to the twenty-sixth embodiment of the present invention;

FIG. 76 is a flowchart illustrating mold design, with attributes beingconsidered in the mold design system, according to a twenty-seventhembodiment of the present invention;

FIG. 77 is a perspective view showing an injection mold device whenindividual attributes are allotted to names of respective parts of thedevice, according to the twenty-seventh embodiment of the presentinvention;

FIG. 78 is a flowchart illustrating design process of holes of the moldparts according to a twenty-eighth embodiment of the present invention;

FIGS. 79A to 79C are perspective views showing interference between thecooling water path and the ejector pin holes according to thetwenty-eighth embodiment of the present invention;

FIG. 80 is a flowchart illustrating design process of manufacturing jigsof the mold parts according to a twenty-ninth embodiment of the presentinvention; and

FIGS. 81A to 81F are views illustrating screen images on the displaydevice when designing the manufacturing jigs according to thetwenty-ninth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

There will now be explained in detail preferred embodiments of thepresent invention with reference to accompanying drawings hereinafter.

An injection mold design system for correcting a profile of a product tobe fabricated into a releasable profile from a mold to design aninjection mold based on a corrected product shape, comprising a storingdevice for storing information of product shape and mold profile, adisplaying device for displaying the product shape or the mold profileon a screen based on the information read from the storing device, aninputting mechanism for inputting designation information necessary forcorrection of the product shape or the mold profile, and a controllingdevice for unloading information of lines or planes being obstructive tocorrection of the product shape and the mold profile into the storingdevice in response to the designation information input by the inputtingmechanism, removing the lines or the planes from the screen, andreplotting the line or the planes on the screen in terms of theinformation of lines or planes unloaded into the storing device afterthe correction operation of the product shape or the mold profile iscompleted.

In the injection mold design system, the lines or the planes beingobstructive to the correction operation are removed from the screen bythe controlling device when the product shape is corrected into areleasable profile. With this process, upon correcting the profile,missing of undercut portions and generation of the line or plane such asfillet being obstructive to correction operation can be prevented, sothat operability may be improved and design error may be prevented. Inthis event, according to the design system of the present invention,since information of the lines or planes removed from the screen arestored in the storing device, the lines or the planes may be replottedon the screen after correction operation of the profile is completed.

In the design system of the present invention, the storing device may beprovided wherein first design items used for correcting the productshape into the releasable profile from the mold, second design itemsused for designing the mold, and third design items used for formingmanufacturing jigs of the mold are stored.

Since the design items being roughly classified into three groups arestored in the storing device, the product designer or the mold designermay correct the product shape in compliance with the first design itemsso as to enable the product to be readily released from the mold. Themold designer may design the mold in compliance with the second designitems. In addition, both the mold designer and the mold manufacturer maydesign the manufacturing jigs in compliance with the third design items.Consequently, since software resources stored in the storing device maybe commonly used by the product designer, the mold designer, and themold manufacturer, design operation of the mold may be conducted easilyand quickly.

In the design system of the present invention, a unit is provided whichmay form dot lines on a constituting plane of the product beingperpendicular to the mold opening direction, and then detect whether ornot the dot lines can be projected onto other constituting plane in themold opening direction.

In case it has been detected that the dot lines formed on theconstituting plane of the product can be projected onto otherconstituting plane in the mold opening direction, the constituting planewould become obstructive in the mold opening direction. Therefore, theconstituting plane may be detected as the undercut portion.

In the design system of the present invention, a unit for connecting anoutermost peripheral profile of the product viewed from the mold openingdirection and line segments of the product designated by the designer soas to extract a split line of the product occupying a certain space maybe provided.

If the outermost peripheral profile of the product viewed from the moldopening direction and the line segments of the product designated by thedesigner are connected, the designer may extract the split line of theproduct occupying a certain space in a manner interacting with thedesign system.

In the design system of the present invention, a device is providedwhich may detect a flat plane constituted with the split line occupyinga certain space, then connect the detected flat plane and one of acircular cylinder surface, a circular cone surface, and a free-formsurface all being designated by the designer, and then form the splitplane to split the product into the cavity and the core.

By connecting the detected flat plane constituted with the split lineand one of the circular cylinder surface, the circular cone surface, andthe free-form surface all being designated by the designer, the designermay form the split plane for splitting the product shape into the cavityand the core in a manner interacting with the design system.

In the design system of the present invention, a device is providedwhich, when the designer has instructed a concerned location against theprofile of the core viewed in the mold opening direction, may detect thedesignated location and a height of the ejector pin for ejecting theproduct from the core and then form a hole profile with dimensions inputby the designer on the designated location.

By detecting the designated location against the core profile viewed inthe mold opening direction and the height of the ejector pin, thedesigner may easily design the hole profile, for example, used for theejector pin for ejecting the product from the core, in a mannerinteracting with the design system.

In the design system of the present invention, a device for displayingon one screen a profile of a mold base constituting the mold and aninstruction window having boxes for inputting respective dimensions ofindividual constituting parts of the mold base therein, and a device forforming data of the mold base in compliance with the input dimensionswhen the designer has input respective dimensions in the boxes of theinstruction windows of the displaying device may be provided.

According to the design system of the present invention, when thedesigner inputs respective dimensions of individual constituting partsof the mold in the instruction windows of the displaying device, data ofthe mold base may be formed in compliance with the input dimensions.Thus, while monitoring the profile of the mold base, the designer maydesign the mold base easily in a manner interacting with the designsystem.

In the design system of the present invention, a storing device isprovided which may store at least information concerning display colorof characters, lines, symbols and regions, information concerning outputmethod of design information of the mold, and information concerningreference values required for each design of the mold. For purposes ofexample, the storing device may be composed of an erasable and writableread-only memory.

According to the design system of the present invention, the storingdevice in which information relating to display color, output method ofdesign information, and reference values are stored may be composed ofthe erasable and writable read-only memory. Therefore, although a plentyof automatic process have been employed, display colors of characters,lines, symbols and regions, output method of information required fordesigning the mold, reference values required for each design of themold, and display method of respective parts data may be modifiedarbitrarily. As a result, the mold design system being mostly suitablefor each designer can be built up.

In the design system of the present invention, a designing device isprovided which may design the mold by using data in the group withselected name when the designer selects the group name of data necessaryfor design of the mold in compliance with the design items of the moldafter the designer allots respective names to groups of data relating tothe design items of the mold.

According to the design system of the present invention, when thedesigner selects a group name of data necessary for design of the mold,the design system may design automatically the mold in accordance withdata included in the group with selected name. Therefore, since thedesigner be able to reduce design items to be input into the designsystem, design operations may be simplified.

In the design system of the present invention, a device is providedwhich may detect a separating distance between a particular hole andother hole of the mold parts, and then compares the separating distancebetween the particular hole and other hole with a preliminary setseparating reference value.

When the separating distance between the particular hole and other holeof the mold parts are compared with the

According to the design system of the present invention, the storingmeans in which information relating to display color, output method ofdesign information, and reference values are stored may be composed ofthe erasable and writable read-only memory. Therefore, although a plentyof automatic process have been employed, display colors of characters,lines, symbols and regions, output method of information required fordesigning the mold, reference values required for each design of themold, and display method of respective parts data may be modifiedarbitrarily. As a result, the mold design system being mostly suitablefor each designer can be built up.

In the design system of the present invention, designing means isprovided which may design the mold by using data in the group withselected name when the designer selects the group name of data necessaryfor design of the mold in compliance with the design items of the moldafter the designer allots respective names to groups of data relating tothe design items of the mold.

According to the design system of the present invention, when thedesigner selects a group name of data necessary for design of the mold,the design system may design automatically the mold in accordance withdata included in the group with selected name. Therefore, since thedesigner be able to reduce design items to be input into the designsystem, design operations may be simplified.

In the design system of the present invention, means is provided whichmay detect a separating distance between a particular hole and otherhole of the mold parts, and then compares the separating distancebetween the particular hole and other hole with a preliminary setseparating reference value.

When the separating distance between the particular hole and other holeof the mold parts are compared with the preliminary set separatingreference value, and if the separating distance between the holes isless than the separating reference value, an abnormal approach betweenthe holes may be detected in the course of design operation. As aresult, design error such as overlapping between the holes may beprevented.

In the design system of the present invention, a device is providedwhich, when the designer designates a range of the manufacturing jigs tobe used for manufacturing the mold parts against the displayed moldparts, may form an ejected profile having a range of the manufacturingjigs of the mold parts as a sectional shape and transfer a profile ofthe mold parts to the ejected profile.

According to the design system of the present invention,

when the designer designates the range of the manufacturing jigs on thedisplayed mold parts, the ejected profile having the range of themanufacturing jigs as the sectional shape may be formed, and the profileof the mold parts may be transferred onto the ejected profile. As aresult, the designer be able to design the manufacturing jigs of themold parts in a manner interacting with the design system.

As for the first design method according to the present invention, inthe injection mold design method for designing the core and the cavityby correcting the profile of the product to be fabricated into areleasable profile from the mold, then arranging the corrected productshape in the mold block being displayed on the screen to provide acavity corresponding to the product shape in the mold block, and thensplitting the mold block, part of lines or planes constituting theproduct shape or the mold profile may be removed temporarily from thescreen, and the lines or planes may be replotted on the screen after thecorrection operation of the product shape or the mold profile beingdisplayed on the screen is completed.

According to the injection mold design method of the present invention,part of the lines or planes constituting the product shape or the moldprofile may be removed temporarily from the screen, and the lines orplanes may be replotted on the screen after completion of profilecorrection when the product shape or the mold profile being displayed onthe screen is corrected. Therefore, the designer may remove lines orplanes being obstructive to required operation from the screen on thedisplay to display only indispensable information on the screen. As aresult, design error due to missing of the undercut, etc. can beprevented.

In this event, for instance, candidates of the split borderline would beselected by forming a flat surface perpendicular to the mold openingdirection, then projecting the product shape onto the flat surface so asto detect its outermost peripheral line, and then drawing a straightline from the outermost peripheral line in the mold opening direction soas to detect entire borderlines of the product shape being intersectingwith this straight line. In general, the split line (parting line) wouldoften be obtained as an outermost peripheral contour of the productshape viewed in the mold opening direction. With the above method, thesplit line may be determined readily by detecting the candidates of thesplit borderline.

As for the second design method of the present invention, in theinjection mold design method for designing the core and the cavity bycorrecting the profile of the product to be fabricated into a releasableprofile from the mold, then arranging the corrected product shape in themold block being displayed on the screen to provide a cavitycorresponding to the product shape in the mold block, and then splittingthe mold block, the undercut portion may be detected by calculating anormal vector on the plane of the product shape and a reference vectorin the mold opening direction, and then detecting a normal vector havingthe opposite direction to that of the reference vector.

According to the second design method of the present invention, theundercut portion may be detected by comparing the normal vector on theplane of the product shape and the reference vector in the mold openingdirection, and then detecting the normal vector with the oppositedirection to that of the reference vector. In other words, the planewith the normal vector having the opposite direction to that of thereference vector always exists in the undercut portion. In the presentinvention, the undercut portion can be automatically detected based onsuch a characteristic. As for the third design method of the presentinvention, in the injection mold design method for designing the coreand the cavity by correcting the profile of the product to be fabricatedinto a releasable profile from the mold, then arranging the correctedproduct shape in the mold block being displayed on the screen to providea cavity corresponding to the product shape in the mold block, and thensplitting the mold block, the split plane may be formed by extending thedesignated split borderline in parallel to the designated direction whenthe mold block is split into the core and the cavity.

As for the fourth design method of the present invention, in theinjection mold design method for designing the core and the cavity bycorrecting the profile of the product to be fabricated into a releasableprofile from the mold, then arranging the corrected product shape in themold block being displayed on the screen to provide a cavitycorresponding to the product shape in the mold block, and then splittingthe mold block, candidates of the split line for splitting the core ofthe mold block into the nest structure may be selected by detecting-abottom of the cavity in the core side, and then extending a peripheralportion of the bottom along the mold opening direction.

According to the fourth design method of the present invention, whenforming the nest structure, the candidates of the split line forsplitting the core of the mold block into the nest structure may beselected by detecting the bottom of the cavity in the core side, andthen extending the peripheral portion of the bottom in the mold openingdirection. Subsequently, by way of example, the candidates of the splitline are numbered in the order from near side of an arbitrary point,then the core may be split by employing odd numbered or even numbered(either one being selected by the designer) candidates of the split lineas the split line, and then the split portion may be determined finallyas the nest structure. In this manner, the nest structure may beautomatically designed.

Next, preferred embodiments of the present invention will be explainedwith reference to accompanying drawings. FIGS. 2 to 81F illustrates aninjection mold design system and an injection mold design methodaccording to embodiments of the present invention.

FIG. 2 shows a configuration of a plastics injection mold design systemaccording to an embodiment of the present invention. In FIG. 2, areference 11 denotes a design data memory (a storing device) for storingproduct shape data (image information) D1 to display a stereoscopicdrawing and a projection drawing of a product to be fabricated. Data D1are binary data.

A reference 12 denotes a base file for storing mold base data D2 as adatabase which may store profiles of cavity and core parts, plates towhich cavity and core parts are clamped, regular parts (screw, ejectorpin, water cooling path, etc.).

A reference 13 denotes a work memory for storing image information (dataD1 to D6, etc.) of a mold model and a product model generated in thecourse of design operation. D3 are element data such as line elements ofthe product (i.e., data such as length, curvature, angle of linesconstituting the product shape) and plane elements of the product (i.e.,data such as size, curvature, angle of planes constituting the productshape). D4 are cavity/core data for defining shapes of the cavity andthe core. D5 are image data required for display on a display 19. D6 areinput data such as control statement, etc.

A reference 14 denotes a product shape correction editor for executingcorrection operation of the product shape so as to enable the product tobe stripped off readily from the mold. The product shape correctioneditor 14 comprises, as respective softwares, a parting line formingsection 41, a draft-sloped plane providing section 42, a shrinkage ratecorrection section 43. The parting line forming section 41 may serve toextract candidates of the parting line from product shape data D1, formthe parting line, detect the undercut portion residing in the productshape, edit the parting line (i.e., rearrange the parting lines havingcontinuous location coordinates into same groups), and check loops ofthe parting lines. The draft-sloped plane providing section 42 may serveto detect respective planes which are to be sloped for easy drafting ofthe product from the mold and respective planes which are preferably tobe sloped (these planes being referred to as “sloped planes”hereinafter), provide the draft slope to the detected sloped planes, andcheck whether or not the product may be released readily from the mold.The shrinkage rate correction section 43 may serve to examine changes ofrespective dimensions of the product according to the shrinkage ratecaused when the resin cures in the mold, and detect the portions of theproduct, for example, which cannot be drafted from the core becauseconvex portions of the core are put into the product. If such portionshave been detected, required treatments are effected such that theprofile of the mold must be modified partially, the draft slope must beprovided to concerned planes by the draft-sloped plane providing section42.

A reference 15 denotes a cavity design editor for designing the cavityin the mold. The cavity design editor 15 comprises, as respectivesoftwares, a cavity/core arranging section 51, a mold splitting section52 including a slide split section 501 and a nest split section 502. Thecavity/core arranging section 51 may generate a mold block such asrectangular parallelepiped or circular cylinder each having largerprofile than that of the product shape on the screen, and then form acavity with a profile identical to the product shape in the mold block.The mold splitting section 52 may form a main parting plane according tothe parting line candidates which are extracted by the foregoing partingline forming section 41, and generate the cavity and the core on thescreen by splitting the mold block by the main parting plane: The slidesplit section 501 may function to form a slide plane being used to splitthe cavity or the core to form the undercut portion as a slidestructure, and check interference between the cavity and the core.Furthermore, the nest split section 502 may generate the parting linefor forming nests on the core side depending upon a depth of the mold,provide priority levels to respective parting lines for splitting thecore, and form nests by splitting the core.

A reference 16 denotes a plate design editor for designing constituentparts necessary for the mold. The plate design editor 16 comprises, asrespective softwares, a mold base arranging section 61, a gate designsection 62, a runner design section 63, a sprue design section 64, a gasvent design section 65, an ejector pin design section 66, a temperatureadjusting structure design section 67, a movable structure designsection 68, and so on. The mold base arranging section 61 may designportions for fixing the mold such as the mold base. The gate designsection 62 may also design location, shape, size, etc. of the gates. Therunner design section 63 may further design shape, location, etc. of therunners to introduce the resin to the mold in the lateral directionthereof. In addition, the sprue design section 64 may design shape,location, etc. of the sprue (sprue runner) to introduce the resin to therunner in the vertical direction of the injection molding machine. Thegas vent design section 65 may design shape, location, size, etc. of thegas vent to exhaust the air from the mold when the resin being injectedinto the mold. The ejector pin design section 66 may design shape,location, etc. of the ejector pin to eject the moldings from the mold.The temperature adjusting structure design section 67 may design thecooling path to cool the mold. Finally, the movable structure designsection 68 may design driving systems (link mechanism) such as runnerstripper plate, cavity plate, and core plate.

A reference 17 denotes a keyboard (an input mechanism) for inputtingcontrol statement etc. to the concerned design system as input data(designation information) D6 by the designer, and instructing switchingof the screen. Auxiliary input tool such as a mouse may be connected tothe keyboard 17. The product or the mold on the screen may be rotated byoperating the mouse or the ten key.

A reference 18 denotes a CPU (Central Processing Unit) for controllinginput/output of design data memory 11, base file 12, work memory 13,product shape correction editor 14, cavity design editor 15, platedesign editor 16, keyboard 17, display 19, printer 20, and other memory21. Depending upon designation information input through the keyboard17, the CPU 18 may execute various functions for temporarily unloadingdata of lines or planes, which being obstructive to the correctionoperation of the product shape or the mold operation currently displayedon the screen, to the work memory 13, then removing the lines or planesfrom the screen, and then replotting the lines or planes on the screenafter the correction operation of the product shape or the mold profilebeing completed.

The CPU 18 further causes the work memory 13 to store historical filegenerated in respective design operations. For instance, the CPU 18stores in time sequence five historical files of data generated in therespective function editors into the work memory 13 in the order fromNo.1 to No.5. In this event, on the assumptions that forming data of thefillet (i.e., reinforce member provided on the intersecting portionbetween more than two planes) data are stored into the historical fileNo.3, that data for providing the draft slope are stored into thehistorical file No.5, and that in addition it is hard to provide thedraft slope because the fillet serves as the obstruction, the CPU 18returns to the historical file No.3 prior to forming the fillet and thenprovides the draft slope using data stored in the historical file No.5to the concerned plane. Subsequently, the CPU 18 returns automaticallyto the historical file No.5 by using data stored in the historical filesNo.3 and No.4.

A reference 19 denotes a display (displaying means) for displaying theproduct model or the mold two or three-dimensionally by reading imageinformation from design data memory 11, database memory 12, or workmemory 13. The display 19 comprises CRT (Cathode Ray Tube), liquidcrystal display, plasma display.

In order to make easy for the designer to recognize the stereoscopicprofile of the product, the design system of the present invention letsthe display 19 display a stereoscopic drawing (isometric drawing, etc.)as shown in FIG. 3A, for example. Referring to FIG. 3A, a reference 1denotes an example of the product to be molded. In this product 1,reinforcing rib 1A, bosses 1B to which parts such as printed circuitboard are fixed, holes 1C into which external terminals, etc. areinserted are provided.

FIG. 3B illustrates kinds of design drawings which are able to bedisplayed by the display 19. Where (1) is a top view of the product 1and FIG. 3C is a top view of the product 1, for example, (2) is a frontview of the product 1 and FIG. 3D is a front view of the product 1, forexample, (3) is a rear view of the product 1, (4) is a right side viewof the product 1, (5) is a left side view and FIG. 3E is a left sideview of the product 1, for example, (6) is a bottom view of the product1, (7) is a right front isometric view showing the product 1three-dimensionally, (8) is a left front isometric view of the same, (9)is a right rear isometric view of the same, and (10) is a left rearisometric view of the same.

With combining these ten kinds design drawings with each other,three-dimensional display screen (window screen) may be depictedtogether in the two-dimensional display screen (main screen) on thedisplay 19. More particularly, when draft slope, nest split, partingplane, gate, runner, ejector pin, and gas vent will be designed, any oneof isometric drawings (7) to (10) of the product 1 may be displayedsimultaneously with plan views of above (1) to (6) on the display 19.Besides, when cavity/core split, cooling path, and link will bedesigned, any one of isometric drawings (7) to (10) of the product 1 mayalso be displayed simultaneously with plan views of above (2) to (5) onthe display 19. In the present design system, these design drawings aredisplayed using three-dimensional CAD tool, CG (Computer Graphics) tool,etc.

Furthermore, the present design system may be equipped with a functionfor removing temporarily from the screen lines or planes beingobstructive to the correction process upon correcting the product shape.For instance, when the profile of the product 1 will be corrected, afillet portion 1D of the product 1 in FIG. 3F may be removed from thescreen, and alternatively an isometric drawing as shown in FIG. 3G maybe displayed. When the correction operation has been completed, thefillet portion may be replotted on the screen.

A reference 20 denotes a printer for outputting profiles and dimensionsof the mold parts on the paper.

A reference 21 denotes other memory. Various design items forsimplifying operations of the mold design system, configuration filesfor supporting the mold design system, and various default valuesrequired for design of the mold parts may be stored in this memory. Aread-only memory in which data are rewritable and erasable may be usedas the memory 21. EPROM and EEPROM are suitable for the memory 21. Thedesign items will be explained later in the twentieth embodiment.Operation of the configuration files will be explained later in thetwenty-sixth embodiment.

Next, an operation of the injection mold design system according to theembodiment of the present invention will be explained. First thedesigner has to read image information of the product 1 from the designdata memory 11 via the keyboard 17 to display the stereoscopic drawingor the projection drawing of either the product 1 or the mold on thedisplay 19. At this time, the designer may temporarily unload data oflines or planes being obstructive to the profile correction operation ofthe product 1 or the mold into the work memory 13 through the keyboardetc. to thus remove these lines or planes from the screen, and maytherefore display only necessary information obviously.

With the above process, while watching or monitoring the screen on whichlines or planes indispensable to the profile correction operation aredisplayed, the designer may correct the profile of either the product 1or the mold.

In the event that the profile of the product 1 should be corrected, forexample, the designer may first generate temporarily on the screen aflat plane on which the profile of the product 1 is projected, then setnew straight lines or new curves on the flat plane, and then project thestraight lines or new curves onto the product 1. The new straight linesor new curves projected onto the product 1 can be extracted as thecandidates of the parting lines to split the mold block into the cavityand the core.

Furthermore, in the case that the profile of the product 1 should becorrected, the designer may first generates temporarily on the screen aflat plane on which the profile lines, edges or borderlines betweenplanes of the product 1 are projected, then set new profile lines, edgesor borderlines between plane elements of the product 1 on this flatplane, and then project onto the product 1 the profile lines, edges orborderlines between plane elements of the product 1 these being newlyset. The new profile lines, edges or borderlines between plane elementsprojected onto the product 1 are extracted as the candidates of theparting lines to split the mold block into the cavity and the core.

As stated earlier, if the candidates of the parting lines have beenextracted preliminarily, the parting lines required for splitting themold back into the cavity and the core may be prepared based on theprofile lines, edges or borderlines between plane elements of theproduct 1 even when the profile of the product 1 must be modified in thecourse of design operation because of correction of shrinkage rate,provision of draft slope.

Under the condition where the stereoscopic drawing and the projectiondrawing of the product 1 are being displayed on the display 19, thedesigner may therefore execute correction of the profile, extraction ofthe parting line, provision of draft slope, etc. of the product 1 in aninteractive fashion.

After the profile correction operation of the product 1 or the moldmodel has been completed, the CPU 18 may plot lines or planes inresponse to the instruction from the designer, using data which havebeen unloaded into the work memory 13.

Subsequently, an injection mold design method of the present inventiontogether with operations of the design system will be explained withreference to FIGS. 2 to 81F. FIGS. 4A to 4C are flowcharts (mainroutine) illustrating design operations of the injection mold. Moredetailed operations in respective steps will be explained in embodimentsdescribed later.

In FIG. 4A, in step A1, candidates of a main parting line for splittingthe mold block into the core and the cavity may be first extracted fromthe product shape in the parting line forming section 41 in the productshape correction editor 14 (see a first embodiment).

In step A2, planes to be sloped are in turn detected from the productshape in the draft-sloped plane providing section 42 (see a secondembodiment).

In step A3, priority levels are then assigned to respective draft-slopedplanes in the draft-sloped plane providing section 42 (see a thirdembodiment). Then, in step A4, draft slopes are provided to the productshape in the draft-sloped plane providing section 42 (see a fourthembodiment).

In step A5, the main parting line is in turn formed based on thecandidates of the main parting line already extracted in step A1 in theparting line forming section 41 (see a fifth embodiment).

In step A6, loop check of the main parting line is then effected in theparting line forming section 41 (see-a sixth embodiment). At this time,if the main parting line has not formed a closed loop (NO GOOD/NG), thenthe process returns to step A5 so as to repeat formation of the mainparting line.

If the main parting line has not been formed as the closed loop in stepA6 (GOOD), then the process advances to step A7 where the undercutportions are extracted from the product shape in the parting lineforming section 41 (see a seventh embodiment).

Thereafter, the process proceeds to step A8 where the parting line for aslide structure is formed in the parting line forming section 41. Theparting line for the slide structure is required when the parting planefor splitting the undercut portions into nest parts would be formed.Subsequently, in step A9, edit operation of the main parting line isexecuted. This edit operation of the main parting line is effected whenthe main parting line would be changed accompanying with formation ofparting lines for a slide core. Substantially, the same process as instep A5 is executed in step A9.

In step A10, loop check of the main parting line is again effected inthe parting line forming section 41. If the main parting line has notformed a closed loop at this time (NG), then the process returns to stepA8 to form the parting line for the slide structure again. If GOOD instep A10, the process advances to step A11.

In step A11, releasability of the product shape is checked in thedraft-sloped plane providing section 42 (see a eighth embodiment). Moreparticularly, ejector force of the ejector pin and shrinkage force ofthe product shape are compared with each other. If ejector force of theejector pin has been less than shrinkage force of the product shape(NG), the process returns to step A4 to repeat provision operation ofthe draft slope. If ejector force of the ejector pin has been in excessof shrinkage force of the product shape (YES), the process advances tostep A12.

In FIG. 4B, in step A12, shrinkage rate of the product shape may becorrected in the shrinkage rate correction section 43. In other words,since individual resins have different shrinkage rates when beingsolidified, sometimes the draft slope must be set again according to theresins. In step A12, a deformation amount of the product shape may becalculated in compliance with shrinkage rate of the resin.

In step A13, the designer would then determines whether or not localmodification of the product shape is required. If the product shape hasbeen determined to be locally modified in step A13 (YES), the processproceeds step A14 so as to modify the profile of the product 1 locally(new draft slope setting, etc.). On the contrary, if it has beendetermined that local modification of the product shape should not beeffected in step A13 (NO), the process proceeds step A15.

In step A15, the cavity/core arranging section 51 in the cavity designeditor 15 commences formation of the mold block. In step A16, thecavity/core arranging section 51 then reads out product shape data D1from the work memory 13. In step A17, the product shape and the moldblock are then overlapped and displayed on the display 19.

Next, in step A18, size and profile of the mold block are checked. If ithas been judged by the designer that size and profile of the mold blockis not appropriate (NO), the process advances step A19. In step A19, thecavity/core arranging section 51 modifies dimension of the mold blockand displays modified dimension. Conversely, it has been determined instep A18 that size and profile of the mold block is appropriate (GOOD),the process advances step A20.

In step A20, a portion in the mold block corresponding to the productshape may be made hollow in the cavity/core arranging section 51. Thehollow portion of the product shape may be formed by inverting theproduct shape portion and the hollow portion mutually (solid/hollowinverting function) in terms of Boolean operation which are executed inthe cavity/core arranging section 51. Cavity/core data D4 obtained byBoolean operation which are executed in the cavity/core arrangingsection 51 are stored in the work memory 13. An isometric drawing asshown in FIG. 5 would be displayed on the display 19. In FIG. 5, areference 100 denotes the mold block, whereas a reference 100A denotesthe mold cavity portion.

In turn, in step A21 in FIG. 4C, the main parting plane for splittingthe mold block 100 may be formed in the mold splitting section 52 (see aninth embodiment).

Thereafter, in step A22, process for splitting the mold block 100 intothe cavity and the core may be started in the mold splitting section 52,and then in step A23 the slide parting line may be formed. Then in stepA24, a slide parting plane may be formed based on the slide parting linein the mold splitting section 52.

In step A25, the mold block 100 is divided into the cavity and the coreby providing the slide parting plane to the mold block 100 in the slidesplit section 501. As shown in FIG. 6, an isometric drawing in which thecavity 3 and the core 4 are split is displayed on the display 19.

Next, in step A26, it would be detected in the mold splitting section 52whether there is caused interference between the cavity 3 and the core 4or not (mold opening interference check). If it has been determined thatmold opening is impossible due to interference between the cavity 3 andthe core 4 (NG), the process advances to step A27 where edit of partinglines and parting planes is repeated in the mold splitting section 52.If it has been determined that mold opening is feasible because of nointerference between the cavity 3 and the core 4 (GOOD), the processadvances to step A28. the mold opening interference check is determineddepending upon whether or not a coordinate value of a certain lineelement is overlapped with other line element.

Next, in step A28, the parting line for splitting the cavity 3 or thecore 4 (usually, core) is formed on the basis of depth of the mold inthe nest split section 502. This is the case where the mold isconstituted with nests by splitting the cavity 3 or the core 4,therefore the nest structure would not be always required if the productshape is relatively simple.

In step A29, priority levels would be given to the parting line forsplitting into the nest in the nest split section 502. Then, in stepA30, the nest split section 502 may form the parting plane of the nest.

In the present embodiment, three kinds of structures such as flat planelocking structure shown in FIG. 7A, and socket and spigot structure andpositioning locking structure shown in FIG. 7B have been prepared inadvance as the parting plane of the nest. The designer may thus selectone of these structures. Hence it would not be necessary for thedesigner to input various data into the system, so that the nest partsfor forming the undercut portion of the product 1 may be readilydesigned, and therefore a burden of the designer may be extremelyreduced.

In step A31, responding to instruction of the designer, part of thecavity 3 or the core 4 may be split into one or plural nests in the nestsplit section 502 (see tenth and eleventh embodiments). For purposes ofexample, with confirming the nests of the mold on the isometric drawingby the display 19, as shown in FIG. 8A, the designer may designate thesectional view of the nest. The designer then instructs a splitdirection of the nest structure, as shown in FIG. 8B. Thereafter, beforeand after the nest structure is split as shown in FIG. 9A, the isometricdrawing may be displayed on the display 19. For this reason, as shown inFIGS. 9B and 9C, three nest structures 1 to 3 for splitting the core 4by the parting plane are displayed on the display 19. The top view ofthree nest structures 1 to 3 projected onto the parting plane as well asthe sectional view (FIG. 9B) of the nest may be displayed on the display19. In FIG. 9C, a hatched portion is a deepest plane of the mold.Likewise, the portion for forming bore portions, etc. of the product 1may be constituted as the nest structure.

In step A32, the mold base for supporting the mold may be arranged inthe mold base arranging section 61 of the plate design editor 16 (see atwelfth embodiment).

Next, in step A33, a gate may be designed in the gate design section 62(see a thirteenth embodiment). In this event, since several kinds ofgate profiles have been stored in the database 12 as patternized data inthe present embodiment, the designer may then design the gate by eitherselecting the kind of the gate or inputting numeric values in compliancewith procedures displayed on the screen.

In step A34, the runner may be designed in the runner design section 63(see a fourteenth embodiment). In this case, since several kinds ofrunner profiles have also been stored in the database 12 as patternizeddata in the present embodiment, the designer may design the runner byeither selecting the kind of the runner or inputting numeric valuesaccording to procedures displayed on the screen.

Subsequently, in step A35, the sprue may be designed in the sprue designsection 64. In this event, since several kinds of sprue profiles havebeen stored in the database 12 as patternized data in the presentembodiment, the designer may design the sprue by either selecting thekind of the sprue or inputting numeric values in compliance withprocedures displayed on the screen.

In step A36, the gas vent may be designed in the gas vent design section65 (see a fifteenth embodiment). In this case, since several kinds ofgas vent profiles have also been stored in the database 12 aspatternized data in the present embodiment, the designer may design thegas vent by either selecting the kind of the gas vent or inputtingnumeric values according to procedures displayed on the screen.

Furthermore, in step A37, profile, size, location of the ejector pin anddiameter of hole for the ejector pin provided in the core may bedesigned in the ejector pin design section 66 (see a sixteenthembodiment). In this event, since several kinds of ejector pin profiles,etc. have been stored in the database 12 as patternized data in thepresent embodiment, the designer may design the ejector pin by eitherselecting the kind of the ejector pin or inputting numeric values incompliance with procedures displayed on the screen.

In step A38, size, location, etc. of the cooling path may be designed inthe temperature adjusting structure design section 67 (see a seventeenthembodiment). In the present embodiment, since several kinds of profiles,etc. of the cooling path are stored in the database 12 as patternizeddata, the designer may design the cooling path by selecting kinds of thecooling path and inputting numerical values according to proceduresdisplayed on the screen.

In step A39, a “link structure” for coupling the runner stripper plate,cavity plate, and core plate may be designed in the movable structuredesign section 68 (see an eighteenth embodiment). In the presentembodiment, since several kinds of the link structures are stored in thedatabase 12 as patternized data, the designer may design the coolingpath by selecting kinds of the link structure and inputting numericalvalues according to procedures displayed on the screen.

Consequently, it would be understood that the plastics injection moldmay be designed via respective steps of the main routine of the designsystem.

Next, respective function portions of the product shape correctioneditor 14, the cavity design editor 15 and the plate design editor 16 inthe design system according to the present invention will be explainedat every embodiment below.

(1) First Embodiment

FIG. 10 is a flowchart illustrating detection operation of profile linesof outermost periphery and though holes of the product according to thefirst embodiment of the present invention. In this process, candidatesof the parting line may be extracted from the profile of the product 1in the parting line forming section 41.

In step B1, the design system may first read the product shape data D1from the design data memory 11 and then display the product shape on thedisplay 19 like as a stereoscopic display shown in FIG. 11. In step B2,the designer may input a mold opening direction of the product shape viathe keyboard. The process then advances to step B3. The design systemmay then switch the display screen on the display 19 to the top view, inwhich the product shape is viewed from the mold opening direction. Thereason why the display should be switched to the top view is that theparting line may often appear as the outermost periphery of the productshape viewed from the mold opening direction. If the parting linedetected in the top view is three-dimensionally displayed once again, itwould become easy for the designer to monitor the parting line. In theevent that the mold opening direction cannot be determined as a certaindirection, then the side view and the bottom view of the product 1 aredisplayed on the display 19.

In step B4, the top view being displayed on the display 19 may bedepicted as a shading display to clarify borderlines of the productshape. Where the shading display signifies color tone of the screen onthe display 19. For instance, insides of the profile line of the product1 are darkened and outside thereof are lightened on the display 19.

In step B5, data of the product shape may be binarized (i.e., a darkportion on the screen is “0” whereas a light portion on the screen is“1”). Then, in step B6, dots constituting the profile line (referred toas “profile dots” hereinafter) may be detected. The borderlines as abovemay be extracted by image processing using Laplacian filter discussedhereinafter.

In image processing using the Laplacian filter, values of four pixels,i.e., upper, lower, right and left pixels B to E into which a targetpixel A displayed as the value “0” or “1” is fetched may be firstexamined. In the case of F<0 in the expression satisfyingF=(B+C+D+E)−4A, portions expressed by the value “1” show the borderlinesof the object side. In the case of F>0, portions expressed by the value“0” show the borderlines of the space side. In the case of F=0, there isno borderline. Consequently, according to this image processing, theprofile lines of the outermost periphery and through holes of theproduct 1 may be detected.

Then, in step B7, it is determined whether or not borderlines (edges)being placed directly beneath the profile lines previously detected maybe detected. This edge detection may be effected by a screen positionfunction. The screen position function signifies that, for example,edges of side portions of the product shape are detected by drawinglines from the plane (outermost periphery forming plane) on the product1 downward in the vertical direction, as shown in FIG. 11. If the edgeshave been detected (YES), then the process proceeds to step B8 where itis checked whether the edges are detected for the first time. If theedges have been detected for the first time (YES), then the processadvances to step B9. In step B9, individual identifiers (ID) indicatingcandidates of the parting lines are attached to edge constituting linesof the product shape data D1. Conversely, if the edges have beendetected for the second time in step B8 (NO), the process then advancesto step B12.

In step B10, display on the display 19 may be changed, and then in stepB11 line elements of candidates of the parting lines are recorded in thework memory 13. In step B12, it is checked whether or not succeedingcandidates of the parting lines are therebelow. If the succeedingcandidates has existed (YES), then the process returns to step B8. Onthe contrary, if there has been no succeeding candidate (NO), then theprocess advances to step B18.

While there has been no edge in step B7 (NO), the process advances tostep B13 where profile dots previously detected may be projected ontothe product shape.

In step B14, curves are formed on the surface of the product shape bythe projected profile dots. Then in step B15, individual identifiers(ID) are attached to the product shape data D1 as the candidates of theparting lines.

Then in step B16, display on the display 19 may be changed. In step B17,the candidates of the parting lines are stored in the work memory 17,and the process then advances to step B18.

In step B18, it is checked whether or not succeeding profile dots arepresent. If the profile dots have not been present (NO), the process isthen terminated. While the profile dots have been present (YES), theprocess then returns to step B7 to repeat either steps B8 to B12 orsteps B8 to B17. As described above, as to all profile dots detectedfrom the top view, the candidates of the parting lines may be detected.Thus profile lines of the outermost periphery and the through holes ofthe product shape are extracted as edges or the borderlines of planepixels.

In this manner, in the injection mold design method according to thefirst embodiment of the present invention, the candidates of severalparting lines may be preliminarily detected. Therefore, even if theproduct shape is modified in the middle of design operation because ofshrinkage rate correction or draft slope provision of the product 1, theparting lines being required for splitting the mold block into the coreand the cavity at desired location can be automatically obtained.

According to the first embodiment of the present invention, it would beunderstood that, since the product shape being three-dimensionallydisplayed has been changed temporarily to that viewed from the moldopening direction, the parting lines can be readily extracted bydetecting the outermost peripheral edge on the top view. Moreover, itwould be apparent that, since the outer edge of the product shape may bedisplayed with different color from other portions on the display 19 orsince the product shape may be classified on the display 19 by differentcolor with defining the outer edge as the boundary, the designer maydiscriminate easily portions to which design process is requested fromportions to which design process is not requested.

(2) Second Embodiment

FIG. 12 is a flowchart illustrating detection process of draft-slopedplanes according to the second embodiment of the present invention. Inthis process, planes to which draft slope should be provided may beextracted from the product shape in the draft-sloped plane providingsection 42.

First, in step C1, the product shape data D1 may be read from the designdata memory 11. In step C2, plane elements of the product shape are readout. The plane elements may correspond to bottom plane, side plane,plane of rising portion of the product 1.

Then, in step C3, the designer may discriminate kinds of the planeelements. If a plane to be inspected has been a flat surface, theprocess proceeds to step C4 where center of gravity of the plane iscalculated. The process then advances to step C7.

If the plane to be inspected has been a free-form surface, then theprocess moves to step C5 where the designer may input the number of gridor the pitch of grid for splitting the free-form surface via thekeyboard 17. It should be noted that the number of grid or the pitch ofgrid may be set preliminarily in the design system.

After this, the CPU 18 may calculate coordinates of a grid intersectingpoint in step C6, and then the process moves to step C7.

In step C7, an inspection point identifier (ID) indicating an inspectionpoint would be assigned to the center of gravity calculated in step C4or the grid intersecting point calculated in step C6. In step C8, a unitnormal vector is calculated on the inspection point. The unit normalvector k derived here can be used as an inspection vector. In step C9,the draft-sloped plane providing section 42 may assign the inspectionpoint ID=k to the inspection point.

Thereafter, in step C10, components of the inspection vector k in themold opening direction may be examined. In case the inspection vector khas been 0 (i.e., it is a parallel plane in the mold opening direction),then the process proceeds to step C11. In step C11, using this plane asthe sloped plane, a sloped plane identifier (ID) for indicating slopedplane would be assigned to the product shape data D1. In step C12, suchsloped plane can be displayed with different color from other planes onthe display 19.

In step C13, a warning such as sound, display, etc. may be issued toinform that the sloped plane has been detected. If in step C10 theinspection vector k has not been 0 (k≠0, i.e., it is a slant plane withrespect to the mold opening direction), it may be determined that theplane should not be sloped and then the process proceeds to step C14.

In step C14, it may be determined whether or not an inspection point tobe succeedingly tested is present. If the succeeding inspection pointhas been present (YES), the process returns to step C7 where it may bechecked whether or not draft slope is needed. But if there has been nosucceeding inspection point in step C14 (NO), then the process advancesto step C20.

In the meanwhile, if the plane to be inspected is a circular cylindersurface in step C3, a unit vector k may be calculated for the centralaxis of the circular cylinder surface. The unit vector can be set as theinspection vector k.

In step C16, components of the inspection vector k in the mold openingdirection may be examined. In case the inspection vector k has been 1(i.e., the central axis of the circular cylinder is parallel to the moldopening direction), then the process proceeds to step C17. In step C17,the sloped plane identifier (ID) for indicating the sloped plane may beassigned to data of the circular cylinder surface in the product shapedata D1. In step C18, such sloped plane may be displayed with differentcolor from other planes on the display 19.

In step C19, it may be informed by sound, display, etc. that the slopedplane has been detected. If in step C14 the inspection vector k has notbeen 1 (k≠1, i.e., the central axis of the circular cylinder surface isperpendicular to the mold opening direction), it may be determined thatthe plane should not be sloped and then the process proceeds to stepC20.

In step C20, it may be determined whether a plane to be succeedinglyinspected is present or not. If the succeeding inspection plane has beenpresent (YES), then the process returns to step C2 where steps C2 to C14are repeated. But if there has been no succeeding inspection plane (NO),then the process is terminated.

With the above processes, it would be obvious that, even if the risingportion of the product shape has been formed by a flat surface, afree-form surface, or a circular cylinder surface, the sloped plane maybe detected. Such detected sloped plane would been stored in the workmemory 13 as element data D3.

(3) Third Embodiment

FIG. 13 is a flowchart illustrating assign process of priority levels todraft slopes according to the third embodiment of the present invention.In this process, priority levels may be assigned to respective slopedplanes detected in the second embodiment in the draft-sloped planeproviding section 42.

In FIG. 13, in step D1, information of sloped plane previouslyregistered may be first read from the work memory 13. In step D2, amagnification center of the draft slope plane may then be calculated.The magnification center is a center of gravity of the product when theproduct shape is projected onto the flat plane being parallel to themold opening direction.

Subsequently, in step D3, the inspection vector k may be calculatedbefore the magnification being effected. In step D4, the product shapemay be magnified in the direction perpendicular to the mold openingdirection Z on the display 19. FIGS. 14A and 14B are isometric drawingsshowing the product shape before and after the magnification beingconducted. Next, in step D5, the inspection vector is calculated afterthe magnification being effected.

In step D6, shrinkage vector as for the sloped plane may be calculated.FIG. 15A is a sectional view showing a certain edge of the product 1before and after the magnification being executed. In FIG. 15A, points(a) and (b) denote respectively a sample point of the edge of theproduct 1 before and after the magnification being effected. FIG. 15Bshows a vector analysis chart of the point (a). S (where a vector symbolbeing omitted) means the shrinkage vector, and a vector component suchthat the core may be clamped by the product. P (where a vector symbolalso being omitted) means the normal vector of the edge plane. Ps (wherea vector symbol also being omitted) means the normal vector of the edgeplane of the product 1 in the shrinkage direction (referred to as“normal vector in the shrinkage direction” hereinafter). In case theshrinkage vector S and the normal vector Ps in the shrinkage directionare opposite to each other (i.e., if it is an outer plane), the moldingsbe able to be easily released from the mold. Therefore this indicatesthat the edge plane need not be draft-sloped (but it would be preferableto provide the draft slope).

FIG. 15C shows a vector analysis chart of the point (b). In case theshrinkage vector S and the normal vector Ps in the shrinkage directionare in the same direction (i.e., if it is an inner plane), the moldingscannot be readily released from the mold. Therefore this indicates thatthe draft slope must always be given to the edge plane.

In other words, in step D7, components of the sample points (a) and (b)in the magnification center direction may be detected from the enlargedview of draft-sloped plane as shown in FIG. 15A. In step D8, vectoranalysis may be effected on the sample points (a) and (b). On the otherhand, if the shrinkage vector S and the normal vector Ps in theshrinkage direction have been in the opposite direction (NO), theprocess advances to step D11 where necessity of the draft slope may berecorded. Then in step D12, a warning to the effect that provision ofthe draft slope is not indispensable but preferable may be displayed onthe display 19.

In step D8, in case both directions of the shrinkage vector S and thenormal vector Ps in the shrinkage direction have coincided with eachother (YES), the process advances to step D9 where indispensablenecessity of the draft slope may be recorded. Then in step D12, awarning to the effect that provision of the draft slope is indispensablemay be displayed on the display 19.

Consequently, depending on the shrinkage vector S and the normal vectorPs in the shrinkage direction, constituent planes of the product 1 maybe classified into the planes to which the draft slope is indispensableand the planes to which the draft slope is preferable.

As discussed earlier, according to the injection mold design method ofthe third embodiment of the present invention, it may be confirmedwhether or not the draft slope is appropriately provided to portions, towhich the draft slope is indispensable, by comparing both directions ofthe shrinkage vector S and the normal vector Ps of the sloped plane ofthe product shape. This is because priority levels have been assigned to“the plane to which the slope plane of the mold is indispensable” instep D9 and “the plane which is preferable to be formed as the slopeplane” in step D11.

(4) Fourth Embodiment

FIG. 16 is a flowchart illustrating provision process of draft slopeaccording to the fourth embodiment of the present invention. In thisprocess, slant may be given to the draft-sloped plane by thedraft-sloped plane providing section 42. As the method for providing theslant, a method for simply inclining the sloped plane, a method forutilizing a slant plane of circular cone, and a method for forming aruled plane which being formed by connecting a shifted base side edge ofthe rising plane and a leading edge of the same by shifting the baseside edge at a distance in the horizontal direction may be listed.

In FIG. 16, in step E1, element data D3 of edge in the product shapepreviously recorded are first read out from the work memory 13.

Then in step E2, the designer may select a sloped plane. If the selectedplane is a flat plane, the process advances to step E3 where, as shownin a broken line circle in FIG. 17B, the sectional view of the edge ofthe product 1 may be temporarily displayed on the display 19. In thebroken line circle in FIG. 17B, a guide curve (reference line) isdisplayed along the edge of the product shape on the display 19. InFIGS. 17A and 17B, the designer may set a reference point at anarbitrary location on the edge line of the product shape, and extend thereference point from the reference point in the X or Y direction of theproduct shape.

In steps E4 and E5, the designer may input angle and rotation directionthrough the keyboard. The process may move to step E6 where, as shown inFIGS. 17A and 17B, the designer may rotate the edge plane of the productshape by input angle in the input rotation direction with the guidecurve as the center to thus form a new plane. Thus a sloped plane can bederived.

As shown in FIG. 18, a new edge may be selected and projected onto theproduct shape. In FIG. 18, a reference 1E denotes an original edgeportion, and a reference 1F denotes a edge portion after offset iseffected by projecting onto the product 1. The isometric drawing of theproduct shape to which the draft slope as shown in FIG. 19 beingprovided may be displayed on the display 19. Then the process advancesto step E17.

Instead, in step E2, if the rising portion of the product shape has beenformed by the free-form surface, the process proceeds to step E7 wherethe guide curve (reference line) may be formed to generate the ruledplane. At this time, a cross section of the edge may be displayedtemporarily as the plan view on the display 19. The cross section of theedge is the rising portion of the product 1. The plan view intersectsperpendicularly with the guide curve.

In the next, in step E8, the edge may be projected to the plan view onthe display 19. In step E9, the designer inputs an offset amount of thebase side edge of the rising plane. In step E10, the design system maythen project the offset edge to the product shape.

In step E11, a triangle can be created with setting offset edge,not-offset edge, and top edge of the rising plane as its three apexes.Then locus of oblique sides of the triangle may be created by moving thetriangle along the guide curve to obtain a ruled plane. The processproceeds to step E17.

Alternatively, in the event that in step E2 formation of a ruled planeby using a circular cone surface has been selected, the process moves tostep E12 where a reference line (guide curve) may be created to form theruled plane. In step E13 and E14, the designer may input angle of thecircular cone and intersecting line calculating pitch. In response tothis input, in step E15, the design system may shift the circular conealong the reference line. Then, for respective intersecting linecalculating pitches, it may calculate intersecting lines between locusof the oblique side of the circular cone or a prolonged line of theoblique side and the bottom.

Then in step E16, the design system may form the ruled plane forconnecting the calculated intersecting lines to the top edge of therising plane. Then the process advances to step E17. This method forforming the ruled plane by using the circular cone may be applicableeven if the bottom is not the flat plane. The intersecting lines may beutilized when the profile would be further corrected in post-process.

In step E17, connecting portion of the ruled plane is processed. Inother words, intersecting lines of the ruled plane in the portion towhich a plurality of planes being connected may be calculated, andoverlapped portions of the ruled plane may then be trimmed. As above, incase the rising portion of the product shape is either the flat surfaceor the free-form surface or unless the bottom is the flat plane, slant(draft slope) may be provided to the product shape. Information as tothe draft slope of the product shape are stored into the work memory 13.

In the mold design method according to the fourth embodiment of thepresent invention, the reference point being newly designated on theflat surface temporarily formed in step E2 may be projected onto therising portion of the product shape, then the guide curve may be createdby extending the new reference point, and then the sloped plane may beformed by inclining the plane or moving the circular cone along theguide curve. The draft slope may therefore be provided to the risingplane of the product shape.

Hence, it would be understood that, if the sloped plane is modifiedaccording to shrinkage rate correction of the product shape, the slopemay be freely modified by assigning angle of the oblique side of thecircular cone again, etc. For this reason, the sloped plane beingsuitable for the product shape may be provided. The best sloped planeenables the product 1 to be released readily from the mold.

In the conventional three-dimensional CAD system, only the function forgiving a slope to flat surface or circular cylinder surface may beeffected, but in the fourth embodiment of the present invention the bestsloped plane may be provided to the product 1, as illustrated in stepsE7 to E11 or steps E12 to E14, even if the sloped plane is formed of thecurve line. As a result, in the fourth embodiment of the presentinvention, in case the sloped plane of the free-form surface should bemodified because of the shrinkage rate correction of the product 1, thesloped plane may be modified arbitrarily by setting a new edge on thetemporarily formed flat plane. Thus the best sloped plane may beprovided when the profile of the product 1 has been changed.

(5) Fifth Embodiment

FIG. 20 is a flowchart for forming the parting line according to thefifth embodiment of the present invention. In this process, the mainparting line for splitting the mold into the cavity and the core may beformed in the parting line forming section 41. In the fifth embodimentof the present invention, steps Fl to F3 and steps F11 to F14 overlapwith other embodiments.

In FIG. 20, in step F1, candidates of the parting line may first beextracted as shown previously in FIG. 10 and, in step F2, parting linecandidate IDs are assigned to respective candidates of the parting line.The process then proceeds to step F3 where the draft slope may beprovided in the manner as shown previously in FIG. 17.

Next, in step F4, the guide curve (reference line) used to provide thedraft slope may also be supplemented as the candidates of the partingline. This is because the guide curve would be required for profilecorrection, etc. of the product 1.

In step F5, the candidates of the parting line may be read from the workmemory 13. In step F6, it may be determined by the designer whether ornot the candidates of the parting line should be used as the mainparting line. If the candidates of the parting line have been used asthe main parting line (YES), the process then advances to step F7. Wherethe line element may be registered as the main parting line in the workmemory 13.

At this time, if the edge cannot be designated because the product shapeis formed of the circular cylinder as shown in FIG. 21A or if theparting line should be provided on the portion other than the edge, thedesigner may first define a flat plane perpendicular to a normal line onthe parting line forming plane (curve forming plane). A curve (orstraight line) may be formed on this plane. The design system thenprojects the curve (or straight line) onto the circular cylinder shapeproduct shape. Consequently, as shown in FIG. 21B, the parting line maybe formed on the product shape 1 with a circular cylinder shape.

After the main parting line being set and the line elements beingrecorded, as above, the designer may cause the display 19 to display theproduct shape (bottom view) viewed in the mold opening direction, asshown in FIG. 22, to designate an outer edge. Thus the display 19 maydisplay such that color tone of the designated outer edge portion has tobe changed, inside and outside with the outer edge as the boundary haveto be displayed by different kind of line, or silhouette has to bechanged in inside/outside of the parting line (marking process).

In step F8, parting line IDs for indicating that the line elements beingused as the main parting line are assigned to the line elements. In stepF9, display on the display 19 may then be changed (marking process) soas to discriminate the concerned line elements from other lines, and theprocess advances to step F10.

On the other hand, if the designer has determined that the candidatesare not used as the main parting line in step F6 (NO), then in step F10it is retrieved whether or not succeeding candidates are present. Ifthere has been succeeding candidates (YES), then the process returns tostep F5 to repeat steps F5 to F10. If there has been no succeedingcandidate (NO), then the process advances to step F11 where loop checkmay be effected to check whether the main parting line can be formed asa closed loop.

Unless the main parting line could be formed as the closed loop (YES),then in step F12 it may be corrected. With monitoring the display 19,the designer may correct the main parting line by indicating edge curve,borderline, etc.

Thereafter, the process then proceeds to step F13 where the parting lineIDs are assigned to edited parting line. In step F14, the display 19 maychange the display on the screen. Then the process returns to step F11.

In the event that there has been no open element (NO), setting of themain parting line may be ended. Element data D3 of the main parting linebeing set are stored in the work memory 13. Consequently, the mainparting line for splitting the mold into the cavity and core has beenformed.

Like the above, according to the mold design method according to thefifth embodiment of the present invention, it would be evident that, asshown in step F7, the projection plane may be defined on theperpendicular plane to the normal direction of the curved surface of thecircular cylinder shape, and the straight line may be formed on thisplane, and then the straight line may be projected onto the curvedsurface of the product. Therefore, the mold design method would beconvenient when the edge cannot be designated to the curved surface orwhen the parting line has to be formed on the portion other than theedge. Furthermore, if the main parting line must be raised intentionallyfrom the plane of the product in the mold opening direction, the partingline may be designed arbitrarily by forming the parting line on the topview of the product and then projecting it onto the side view of theproduct.

(6) Sixth Embodiment

FIG. 23 is a flowchart illustrating check process of the parting lineaccording to the sixth embodiment of the present invention. In thisprocess, it may be checked automatically whether or not the main partingline is formed as the closed loop in the parting line forming section41. If OK, it would be set as the parting line.

In FIG. 23, in step G1, element data of the parting lines may first beread from the work memory 13. In step G2, loop check of the partinglines may be commenced. The designer may designate the element of theparting lines to start loop check. As shown in FIGS. 24A and 24B, theelements of the parting lines are labelled by ePL(n).

Then, in step G3, as for the elements of the parting lines designated bythe designer, the loop numbers are assigned to the parting lines, and instep G4 coordinates of a starting point knot may be calculated. Theparting lines assigned by the loop number are collected into a group asan element. Coordinates of starting point of the parting lines are givenby (xn^(s), yn^(s), zn^(s)) and coordinates of end point of the partinglines are given by (xn^(E), yn^(E), zn^(E)).

In step G5, elements ePL(n) of other parting lines connected to objectparting line may be retrieved. Then, in step G6, it may be decidedwhether or not there are elements of the parting lines having knots onthe same coordinates. That is, it may be detected whether startingpoints of the elements ePL(n) coincide with end points of the elementsePL(n−1), or whether end points of the elements ePL(n) coincide withstarting points of the elements ePL(n+1).

In case it has been determined that there are elements of the partinglines having knots on the same coordinates (YES), then the processadvances to step G7. In step G7, it may be determined whether or notthey are starting point knots of the parting lines. If they have beendetermined to be the starting point knots (YES), then in step G8 itwould be decided whether the succeeding loop number exists or not. Ifthe succeeding loop number has existed (YES), then in step G9 elementdata D3 of the parting lines having the succeeding loop number may beread out.

Then, returning to step G4, coordinates of the starting point knots maybe calculated. While, if it has been decided that there is no partingline having knots on the same coordinates in step G6 (NO), then in stepG10 elements of the parting lines being connected to other parting linesare displayed.

In step G11, it may be decided whether or not plural elements beingconnected to other parting lines are present. In case the number ofelement has been decided as a plural (YES), then in step G12 where otherparting lines are checked. The designer may designate elements of theparting lines to be checked at this time. For the parting linesdesignated by the designer, it may be judged in step G13 whether or notloop number of the designated parting lines is existing one. If the loopnumber of the designated parting lines has been decided to be existingone (YES), then the process moves to step G15. Conversely, if it hasbeen decided that the loop number of the designated parting lines is notexisting one (NO), then in step G14 loop numbers are assigned tonon-selected parting lines. Then in step G15, coordinate values ofsucceeding knots may be calculated.

Thereafter, returning to step G5, elements of the parting lines beingconnected to other parting lines are retrieved. In step G6, it may bedecided whether or not there are elements of the parting lines havingknots on the same coordinates. In case it has been determined that thereis no element of the parting lines having knots on the same coordinates,i.e., that the parting line does not constitute a closed loop (NO), thenthe process advances to step G16. An error message is displayed on thedisplay 19, then the process goes to step G17 where abnormal terminationis effected.

In step G8, if it has been determined that there is no succeeding loopnumber (NO), then in step G18 it may be examined whether elements ofunchecked parting lines exist or not. If there have been elements ofunchecked parting lines (YES), the process returns to step G3 to repeatsteps G3 to G15 etc. If there has been no unchecked parting lines (NO),the process may be terminated since all grouped parting lines have beenformed respectively as closed loops. Thus check of the parting lines hasbeen completed.

As has been stated above, in the mold design method according to thesixth embodiment of the present invention, by checking in step G6according to the coordinate retrieval result of line elements of theparting lines whether there are elements of the parting lines havingknots on the same coordinates, it may be checked automatically whetheror not the parting lines may constitute the closed loop. Therefore, ifthe parting lines have been formed as the closed loop, it can be graspedin the initial stage of design that “the mold block 100 can be splitinto the cavity and the core”, whereas if the parting lines have notbeen formed as the closed loop, it can be found in the initial stage ofdesign that “the mold block 100 cannot be split into the cavity and thecore”. Overlapping of line elements of the parting lines may be checkedby the check function.

According to the sixth embodiment of the present invention, it would beevident that line elements of the parting lines may be grouped byallotting loop number to the line elements of the parting lines in stepG3. Hence, batch data processing may be effected when the split planefor splitting the mold block 100 into the cavity and the core is formed,or when individual identifiers (IDs) such as priority level areassigned.

(7) Seventh Embodiment

FIG. 25 is a flowchart for detecting undercut portions in the productshape according to the seventh embodiment of the present invention. Inthis process, the parting lines constituting the opening portion (hole)of the product 1 in the parting line forming section 41. In the mold,the undercut portion may be formed as a nest structure. In the neststructure, the moldings must be released from the mold by sliding thesplit portions.

In FIG. 25, in step H1, product shape data D1 to which the main partingline has been determined may first be read from the work memory 13. Instep H2, the direction of retrieval vector for retrieving the undercutmay be set.

As shown in FIG. 26, the retrieval vector is −Z component, which isopposite direction to the vector in the mold opening direction. The moldopening direction may be defined as the direction for splitting the moldblock 100 into the cavity and the core (see FIG. 5). Accordingly, theplane elements having their normal vectors in the same direction as theretrieval vector become obstructive when the mold block 100 is splitinto the cavity and the core.

In step H3, plane elements constituting the product shape may be readout, and in step H4 components of the normal vector on the product planewith respect to the retrieval vector may be examined. As shown in FIG.26, if the normal vector is opposite to the direction component of theretrieval vector, i.e., positive (+) or if it is 0, the progress goes tostep H10 where succeeding plane elements are retrieved since it is notobstructive to the mold opening. As shown in FIG. 27, the opening holeon the upper surface of the product 1 with the direction of itsretrieval vector of 0 is not the undercut portion. In order todiscriminate such opening portion from the undercut portion, the openingportion may be displayed with different color tone on the display 19.

If the normal vector is identical to the direction component of theretrieval vector, i.e., negative (−), the process advances to step H5.For instance, the designer may input the number of grid to split theplane since as shown in FIG. 26 the undercut portion being obstructiveto the mold opening is present. In step H6, the CPU 18 may calculategrid intersecting points including parting lines of the plane serving asthe undercut portion.

In step H7, straight lines (semi-infinite straight lines) which extendin the (−) direction of the retrieval vector using the grid intersectingpoints as the starting points are formed. In step H8, it may be detectedwhether product planes intersecting with these semi-infinite straightlines exist or not. If there have been product planes intersecting withthe semi-infinite straight lines (YES), the process proceeds to step H9where they can be registered as the undercut portions. Undercut IDs areassigned to the product shape data D1.

Unless product plane intersecting with the semi-infinite straight lineshas been detected in step H8 (NO), no undercut portion can beregistered. The process then goes to step H10 where it is checkedwhether or not plane elements to be succeedingly inspected are present.If there have been plane elements to be succeedingly inspected (YES),the process returns to step H3. Plane elements constituting the productshape may then be read out. Steps H3 to H9 may then be repeated. In stepH10, if there has been no plane element to be succeedingly inspected(NO), the process may be ended. As a result, the undercut portions ofthe product 1 may be detected.

In this manner, in the mold design method according to the seventhembodiment of the present invention, the undercut portions beingobstructive to release of the cavity 3 from the core 4 of the mold maybe detected by retrieving the normal vector of the product shape in thesame direction as the retrieval vector. Thus, the rising portions of theproduct shape, the undercut hidden behind the boss, etc. cannot bemissed. By detecting the undercut, the core of the mold may be designedas the nest structure.

In addition, according to the seventh embodiment of the presentinvention, it would be obvious that, if the closed loop of other partingline is on the inside of the closed loop of a certain parting line, theclosed loop candidate of this inner parting line then shows the holeprovided in the product 1 other than the undercut portion. Therefore,the mold can be designed without escaping the rising portions of theproduct shape, the undercut hidden behind the boss, etc.

(8) Eighth Embodiment

FIGS. 28A and 28B are flowcharts illustrating check process ofreleasability of the draft-sloped plane according to the eighthembodiment of the present invention. In this process, it may be checkedin the draft-sloped plane providing section 42 whether or not themoldings can be easily released from the mold.

In FIG. 28A, in step I1 the product shape data D1 are read from thedesign data memory 11. In step 12 the plane elements of the productshape are read from the work memory 13. The designer may designate theplane element of the parting lines. The plane element can be selectedfrom flat surface, free-form surface, and circular cone surface.

In step 13, the plane element derived previously in FIGS. 3C to 3E maybe classified. If the plane element is the flat surface, then in step I4where inspection points may be read.

In step I5, the shrinkage vector may be read, and then in step I6 anarea may be calculated. In step I7, shrinkage force caused upon draftingthe moldings may be calculated by multiplying dimension and area of theshrinkage vector together.

On the contrary, if the plane element is the free-form surface in stepI3, then in step I8 the inspection point may be read, followed byreading of the shrinkage vector in step I9. Subsequently, in step I11,like the case where the plane element is the flat plane, the shrinkageforce may be calculated by multiplying dimension and area of theshrinkage vector together.

In step I12, it would be checked whether or not a succeeding inspectionpoint is present. If it has been judged that the succeeding inspectionpoint is present (YES), then the process returns to step I8 so as toread the inspection point. If it has been judged that the succeedinginspection point is not present (NO), then the process goes to step I13where the shrinkage forces of the product 1 are summed entirely. Theprocess proceeds to step I18.

Furthermore, if the plane element is the circular cone surface in stepI3, then in step I14 the shrinkage vector may be read, thereafter instep I15 the area may be calculated. Next, in step I16, the shrinkageforce may be calculated by multiplying dimension and area of theshrinkage vector together. In step I17, whole shrinkage forces aresummed and the process goes to step I18.

In step I18, it may be decided whether succeeding plane element ispresent or not. If the succeeding plane element has been present (YES),then the process returns to step I2 so as to repeat steps I3 to I18.Unless there has been the succeeding element in step I18 (NO), then instep I19 stick strength of the moldings to the mold may be calculated bymultiplying the total shrinkage force by a certain coefficient.

After this, in step I20, ejector force of the ejector pin and stickstrength of the moldings are compared with each other. In the event thatejector force of the ejector pin has been less than stick strength ofthe moldings (NO), the process then returns to draft slope step of themain routine in FIG. 4A.

In the event that in step I20 ejector force of the ejector pin has beenmore than stick strength of the moldings (YES), the process then goes tostep I22 where total shrinkage force of the core plane may becalculated. Then in step I23, total shrinkage force of the cavity planemay be calculated.

In step I24, the total shrinkage force of the core plane and the totalshrinkage force of the cavity plane may be compared with each other. Incase the total shrinkage force of the core plane has been larger thanthe total shrinkage force of the cavity plane (YES), the process may beterminated. On the contrary, in case the total shrinkage force of thecore plane has been smaller than the total shrinkage force of the cavityplane (NO), the process then returns to draft slop provision step I4 inthe main routine in FIG. 4A so as to form the draft slope once more.

With the above processes, it would be apparent that it may be checkedwhether or not the moldings can be easily released from the mold (i.e.,releasability of the draft-sloped plane may be checked).

(9) Ninth Embodiment

FIGS. 29A to 29C are flowcharts illustrating formation process of theparting plane according to the ninth embodiment of the presentinvention. In this process, in the mold splitting section 52, the moldblock 100 may be formed to surround the product shapethree-dimensionally and then the cavity corresponding to the productshape may be formed in the mold block 100. A parting line plane 200 maybe formed based on the candidates of the parting lines, and then themold block 100 may be split based on the parting line plane 200 to formthe cavity and the core.

In FIG. 29A, in step J1, the cavity/core data D4 in which the actualproduct shape and the space profile to enclose the actual product shapeare inverted may be read from the work memory 13. In step J2, theelement data D3 of the parting lines may be read from the work memory13.

In step J3, the designer may classify the mold block 100. For purposesof example, if the mold block 100 is the rectangular parallelepiped asshown in FIG. 30A, then in step J4, according to the instruction fromthe designer, a coordinate system may be defined wherein a Z axis is themold opening direction, an X axis is a longer side and a Y axis is ashorter side.

In step J5, it may be detected whether or not the parting line whichintersects with the plane having the element X=0 of the mold block 100is present. Where the plane having the element X=0 signifies the planeof the mold block 100 placed in Z Y directions. If the parting linewhich intersects with the plane having the element X=0 has been detectedin step J5 (YES), then in step J6 the parting line is split at anintersecting point with the plane having the element X=0, and then theprocess goes to step J7. Unless the parting line intersecting with theplane having the element X=0 has been detected in step J5 (NO), then instep J7 the mold split section 52 may detect position of the elementePL(n) of the parting line.

If the element X>0 of the mold block 100 has been detected in step J7(YES), then in step J8 the parting line may be projected onto thesurface of the mold block 100 in the +X direction. Conversely, if theelement X<0 has been detected in step J7 (NO), then in step J9 the moldsplit section 52 may project the parting line onto the surface of themold block 100 in the −X direction.

In addition, in step J10, it may be detected whether or not the partingline which intersects with the plane having the element Y=0 of the moldblock 100 is present. Where the plane having the element Y=0 signifiesthe plane of the mold block 100 placed in the Z·X directions. If theparting line which intersects with the plane having the element Y=0 hasbeen detected in step J10 (YES), then in step J11 the parting line issplit at an intersecting point with the plane having the element Y=0,and then the process goes to step J12.

Unless the parting line intersecting with the plane having the elementY=0 has been detected in step J10 (NO), then in step J12 the mold splitsection 52 may detect position of the element ePL(n) of the partingline. If the element Y>0 of the mold block 100 has been detected in stepJ12 (YES), then in step J13 the parting line may be projected onto thesurface of the mold block 100 in the +Y direction. On the contrary, ifthe element Y<0 has been detected in step J12 (NO), then in step J14 themold split section 52 may project the parting line onto the surface ofthe mold block 100 in the −Y direction.

In step J15, a ruled plane may be formed between the curve projectedonto the mold block 100 and the parting line provided on the productshape. In step J16, the curve projected onto the mold block 100 and theparting line provided on the product shape are connected to each other.As a result, four parting planes 200 have been formed in the X·Ydirections.

In step J17, as shown in FIG. 30B, the parting plane 200 may be depictedon the display 19. In FIG. 30B, the parting line provided on the productshape may be projected onto four side surfaces of the mold block 100.FIG. 30C illustrates offset parting line projected onto four sidesurfaces of the mold block 100 in an enlarged manner. In other words,coordinates of the edges of the projected parting line are extended tothe corners of the mold block. Otherwise, the parting line may be formedon the edge portions of the mold block by magnifying edge portions ofthe product shape with a particular point on the flat surface includingtwo parting lines as the magnification center and then projecting themonto the mold block. In this manner, the parting plane 200 for splittingthe mold block into the cavity 3 and the core 4 has been formed. In FIG.30C, a single arrow line signifies the parting line provided on theproduct shape, and a double arrow line signifies the parting lineobtained by magnifying the curve projected onto the mold block 100.

If the designer has designated the circular cylinder as the profile ofthe mold block 100 in step J3, then in step J18 the coordinate systemmay be defined wherein the mold opening direction is set as a Z axis andX and Y axes are not particularly specified.

In step J19, a directional vector for similar magnification of theelements of the parting line may be calculated. Where the directionalvector for similar magnification signifies a line segment which may liefrom an origin of the parting line, being to be magnified arbitrarily,to a definition point of the parting line.

The process then advances to step J20 where a Z axis component of theforegoing directional vector for similar magnification may be set tok=0. In step J21, the elements of the parting line may be magnified inparallel to the X·Y plane, and then the parting line may be projectedonto the surface of the mold block 100. Here previously modified vectormay be used. In step J22, the mold split section 52 may form a ruledplane between the curve projected onto the surface of the mold block 100and the parting line provided on the product shape 1.

While, if it has been decided in step J3 that the mold block 100 is notthe rectangular parallelepiped nor the circular cylinder, then in stepJ23, as another case, the coordinate system may be defined wherein themold opening direction is set as a Z axis and X and Y axes are notparticularly specified. In step J24, the designer may input the plane tobe projected, i.e., the objective projection plane, into the mold splitsection 52.

Then, in step J25, a projection directional vector may be input. In stepJ26, the direction of the projection directional vector may be set tothe X′ axis. Subsequently, in step J27, it may be detected whether theparting line which intersects with the plane having the element X′=0 ofthe mold block 100 is present or not.

If the parting line intersecting with the plane having the element X′=0is present in step J27 (YES), then in step J28 the parting line may besplit at the point intersecting with the plane having the element X′=0.Then, the process proceeds step J29. If there has been no parting linewhich intersects with the plane having the element X′=0 in step J27(NO), then in step J29 position of the line elements of the parting linemay be detected. In case X′>0 in step J29 (YES), then in step J30 theparting line may be projected onto the surface of the mold block 100 inthe +X′ direction. Conversely, in case X′<0 in step J29 (NO), then theprocess goes to step J30.

Then, in step J31, the ruled plane may be formed between the curveprojected onto the mold block 100 and the parting line provided on theproduct shape.

In step J32, it may be detected whether or not a succeeding projectiondirection remains. If the succeeding projection direction has beendetected in step J32 (YES), then the process returns to step J24 so asto execute steps J24 to J32 repeatedly. Instead, unless the succeedingprojection direction has been detected in step J32 (NO), then theprocess may be ended.

With the foregoing processes, the parting plane 200 for splitting themold block 100 into the cavity 3 and the core 4 may be formed.Cavity/core split information are stored as cavity/core data D4 into thework memory 13. The cavity may constitute the fixed side of the mold andthe core may constitute the movable side of the mold. The cavity and thecore can be registered as individual parts.

In this fashion, according to the mold design method of the ninthembodiment of the present invention, it would be apparent that theparting plane 200 may be formed in the mold split section 52 byextending the parting line for splitting the mold block 100 in parallelto the designated direction. Therefore, position coordinates of theparting line may be utilized as the starting point coordinates of theparting plane 200. Accordingly, since the parting plane 200 may beformed by merely designating the position coordinates of the partingline, a burden of the designer can be significantly reduced in contrastto the case where all new coordinates have to be input as the partingplane 200. Besides, man-hour for design can be extremely cut down.

According to the ninth embodiment of the present invention, it should benoted that the parting plane 200 may be formed by providing an arbitraryoffset amount to the parting line for splitting the mold block 100 andthen magnifying the parting line in the designated direction. Therefore,only by designating the magnified position of the parting plane 200, thedesigner can clearly grasp, for example, which plane may split the moldblock 100 being displayed in three-dimensional fashion into the core andthe cavity.

According to the ninth embodiment of the present invention, it would beevident that, since the parting plane 200 for splitting the mold block100 into the core and the cavity may be displayed three-dimensionally inthe perspective view, the convex portion of the mold block 100 servingas the core of the mold can be confirmed from the concave portion sideof the mold block 100 serving as the cavity of the mold. In this manner,the parting plane 200 passing through the parting line can be formedeffectively.

(10) Tenth Embodiment

FIGS. 31A to 31C are flowcharts illustrating detection process of adepth of the mold and split candidate position according to the tenthembodiment of the present invention. In this process, in order tofacilitate fabrication of the cavity 3 and the core 4, the cavity 3 andthe core 4 may be formed as the nest structure depending upon the depthof the mold in the nest split section 502. In order to form the neststructure, nest split candidates must be detected based on the depth ofthe mold.

In FIG. 31A, in step K1, cavity/core data D4 may first be read from thework memory 13. In step K2, the flat surface may be positioned on alocation at which the depth of the mold must be inspected. In step K3, asectional shape of the mold may be displayed on the display 19 toinspect the depth. Here, as shown in FIG. 32, a neutral plane of themold may be displayed on the display 19. Where the neutral planesignifies a plane formed by collecting thickness central points of themoldings, and it further includes the plane separated from the wallsurface at a constant distance in the concave portion, as shown by adot-dash line in FIG. 32. In FIG. 32, a reference 100A denotes a cavityportion constituting the moldings; 100B, split line candidate portions;100C, deepest portion of the mold; 100D, portion wherein its Z componentbeing suddenly changed on the neutral plane (abruptly changingconcave/convex portion); and 100E, portion corresponding to the rib ofthe moldings, etc. on which the neutral plane must be branched.

In step K4, the thickness central line may be detected by retrieving(decaying) the cavity 3 (cavity portion). The thickness central linesignifies a line which may pass the center in the edge thicknessdirection of resin of the moldings.

In step K5, a reference line used for measuring the depth of themoldings may be defined. In step K6, an upper limit value for providinga depth detection range may be input according to the instruction issuedfrom the designer.

In steep P7, pixels on the thickness central line may be read. Then instep K8, the straight line passing the pixels on the thickness centralline and being in parallel to the mold opening direction may be formed.In step K9, an intersecting point of the previous straight line and thereference line may be calculated.

In step K10, a distance between pixels on the thickness central line andthe intersecting point may be calculated. Then the distance per onepixel may be calculated in units of mm.

Then in step K11, the distance previously calculated and an upper limitvalue of the depth may be compared with each other. In other words, itmay be determined whether or not the calculated distance is longer thanthe upper limit value of the depth. If the distance previouslycalculated has been longer than the upper limit value of the depth(YES), then the process proceeds to step K12. On the other hand, if thedistance previously calculated has been less than the upper limit valueof the depth (NO), then the process advances to step K15.

In step K12, edges near the pixel on the thickness central line may bedetected. The edge detection may be done by the screen position functionwhich has already been explained. Edges of the deepest portion of themold can thus be detected. Line elements extending from these edges aredecided as candidates of the nest split line.

In step K13, lines extending from the edges of the deepest portion maybe registered as candidates of the nest split line. This registrationmay be done by assigning the nest split line candidate ID and algorithmto the cavity/core data D4. The algorithm would determine draft order ofrespective nest structures.

In step K14, for easy monitoring of the designer, the isometric drawingof the mold as shown in FIG. 6 may be displayed with different colortone on the display 19. In step K15, it may be checked whether or notsucceeding pixels is present. If there have been succeeding pixels(YES), then the process returns to step K7 where pixels on the thicknesscentral line may be read. Then, succeeding steps P8 to P14 would beeffected repeatedly. With the above processes, candidates of the nestsplit line of the mold can be detected.

In step K16, the number of pixel near the depth to be detected may beinput. As the number of pixel, (odd number)2 −1 may be input dependingon neighboring pixels the depth of which is to be detected. For example,the number of pixel is 3²−1=8, 5²−1=24, or the like. Designation ofinput pixel may be input by the designer.

In step K17, adjacent pixels may be detected in the pixel matrix havingthe neighboring pixel number designated by the designer. If the adjacentpixels has been detected (YES), the process goes to step K21. Unless theadjacent pixels has been detected (NO), then in step K18 edges near thepixel may be detected. Such edge detection may be effected by screenposition function. In step K19, the edges may be registered ascandidates of the nest split line. Upon registering the edges, nestsplit line candidate ID and algorithm are assigned to the cavity/coredata D4. The algorithm may determine draft order of respective neststructures.

In step K20, for easy monitoring of the designer, the isometric drawingof the mold may be displayed with different color tone on the display19. In step K21, it may be checked whether or not succeeding pixel ispresent. If the succeeding pixel has been present (YES), then theprocess returns to step K17 where pixels on the thickness central linemay be read out. Thereafter, succeeding steps K18 to K20 would berepeated. Thus circumstances around the adjacent pixels can be found atthe candidate positions for splitting the mold in the depth direction.

In step K22, an upper limit value (absolute value) of gradient rate(rate of change) of the depth may be input. In step K23, pixels atcandidate locations for splitting the depth may be read. In step K24,the number n of pixel may be input to approximately calculate thegradient of the depth. Then in step K25, right and left side gradientsas for the pixel being read out from the work memory 13 may becalculated.

In step K26, difference between the right and left side gradients may becompared with the upper limit value of change rate of the gradient. Ifthe difference between the right and left side gradients has beengreater than the upper limit value of rate of change of the gradient(YES), then in step K27 edges near the pixel may be detected. The edgedetection may be executed by screen position function. In step K28, theedges may be registered as candidates of the nest split line. Uponregistering the edges, nest split line candidate ID and algorithm areassigned to the cavity/core data D4. The algorithm may determine draftorder of the nest structures.

In step K29, for clear monitoring of the designer, the isometric drawingof the mold may be displayed with different color tone on the display19. Then the process goes to step K30. On the contrary, if thedifference between the right and left side gradients has been less thanthe upper limit value of change rate of the gradient in step K26 (NO),then in step K30 it may be checked whether or not succeeding pixel ispresent. If the succeeding pixel has been present (YES), then theprocess returns to step K26 where the difference between the right andleft side gradients of the pixel and the upper limit value of changerate of the gradient may be compared with each other. Steps K27 to K29may be performed one more time. While, if there has been no succeedingpixel in step K30 (NO), then the process would be terminated. With theabove processes, the nest split candidates for forming the nestcorresponding to the depth of the mold may be detected.

As described above, according to the mold design method according to thetenth embodiment, it should be noted that, by extending the edge pointnear the deepest position from the split plane of the mold block 100 inthe split direction of the mold block 100, candidates of the splitborderline for splitting the core of the mold block 100 into the nestparts may be extracted.

Therefore, even if the sectional shape of the product 1 viewed from thedirection being parallel to the split direction of the mold block 100 iscomplicate like a comb shape, the optional item can be offered to thedesigner which enable the nest profile to be most readily formed as themold parts. As a result, even if the mold cavity should be formed as adeep pocket shape which would be of course difficult to be formed, thecore 4 may be split into the most suitable nest profile.

(11) Eleventh Embodiment

FIG. 33 is a flowchart illustrating assignment process of prioritylevels to nest split line candidates according to the eleventhembodiment of the present invention. In this process, the prioritylevels may be assigned to the parting lines for splitting the cavity 3and the core 4 in the nest split section 502.

Referring to FIG. 33, in step L1, the cavity/core data D4 in which thenest split line candidates has been detected may be read from the workmemory 13. As shown in FIG. 33, the neutral plane may be displayed onthe display 19.

In step L2, with respect to both the portions to which large surfaceunevenness of the mold has to be required and the portions in which thecavity portion of the mold has to be formed as a deadend portion, thesplit line candidates may be read. The split line candidates may berecognized by IDs of the cavity/core data D4 read out from the workmemory 13.

In step L3, the split candidate lines may be displayed on the neutralplane on the display 19 according to the split line candidates derivedfrom IDs of the cavity/core data D4. The split candidate lines areillustrated by the broken line, as shown in FIG. 34. Then lines being inparallel to the mold opening direction (Z) and passing the splitcandidate lines are drawn. The parallel lines are illustrated by thesolid lines, as shown in FIG. 34.

After this, in step L4, the designer may instruct the starting points toassign priority levels. Then in step L5, lines being perpendicular tothe mold opening direction and passing the starting points are drawn. Instep L6, such points may be formed that pass the above lines beingperpendicular to the mold opening direction and passing the startingpoints, and pass the split candidate lines (shown by dots in thesectional view), and also intersect with the parallel lines in the moldopening direction.

In step L7, intersecting point numbers may be assigned in sequence fromthe starting point side in respective right and left directions. Inother words, R1={circle around (1)}, R2={circle around (2)}, R3={circlearound (3)} . . . are labeled in sequence to the right side, andL1={circle around (1)}, L2={circle around (2)}, L3={circle around (3)} .. . are labeled in sequence to the left side.

In step L8, it may be determined whether or not the intersecting pointnumbers are either odd number or even number. If the intersecting pointnumbers have been even number (YES), then in step L9 where the candidatelines may be registered as the candidate with higher priority level. IDsmay be assigned split line candidates of the cavity/core data D4.

In the next, in step L10, with changing color of the portions to beselected as the split line candidates, the display may be switched fromthe neutral plane of the mold to the isometric drawing on the display19. The process then proceeds to step L11. Alternatively, if theintersecting point numbers have been even number in step L8 (YES), thenin step L11 it may be checked whether or not succeeding intersectingpoint is present. If there is the succeeding intersecting point in stepL11 (YES), the process returns to step L8 where it may be determinedwhether the intersecting point numbers are either odd number or even

number. Then following steps L9 and L10 would be repeated.

If there is no succeeding intersecting point in step L11 (YES), then theprocess may be ended. With the above, priority levels may be assigned tothe parting lines for splitting the cavity 3 and core 4.

In this manner, in the mold design method according to the eleventhembodiment, according to rules caused by the restriction on process forthe mold parts, priority levels have been assigned to the candidates ofthe split borderlines for the nest parts in step L9. Therefore, thedesigner may design the nest profile to be most readily formed as themold parts by selecting the candidates of the split borderlines of thenest parts in compliance with the priority levels even if the sectionalshape of the mold cavity is complicate like the comb shape. As a result,the designer having no experience can design easily the nest structure.

(12) Twelfth Embodiment

FIGS. 35A and 35B are flowcharts illustrating arrangement process of themold base according to the twelfth embodiment of the present invention.In this process, the mold base may be arranged for fixing the mold, andthe mold may be fixed by the plates in the mold base arranging section61.

Referring to FIG. 35A, in step M1, the cavity/core data D4 may first beread out from the work memory 13. In step M2, the mold base having asuitable size in which the cavity and the core can be housed may be readout. The mold base constitutes the plate for fixing the mold. In thetwelfth embodiment of the present invention, as for the method forfixing the cavity and the core to the plate, clamping screw or rib,fixing position, nominal designation of thread or rib dimension etc. maybe patternized. Mold base data D2 obtained by patternizing the fixingparts have been stored in the base file 12.

In step M3, the mold base arranging section 61 may arrange the cavityand the core in the mold base. In step M4, the profile (mold block) ofthe cavity and the core may cut off from the plate of the mold base. Inthe mold split section 52, cutting-off of the profiles of the cavity andthe core may be effected by the solid/hollow inversion function in termsof Boolean operation.

In step M5, parts of the cavity and the core may be read out. In stepM6, the designer may specify the parts serving as the base.

In step M7, the designer may select the fixing structure of the mold. Inthe event that the mold should be fixed by the pocket holes and screws,then in step M8 the depth of the pocket hole may be input. Theconnection diagram between the plate and the block, as shown in FIG. 36,may be displayed on the display 19. In FIG. 36, a reference 101 denotesa plate in which a pocket hole (spot facing hole) 102 is formed, and areference 201 denotes a block in which a tapped hole 104 is formed. Theplate 101 may support the block 201 which holds the nest therein. FIG.36 illustrates the case wherein the plate 101 and the block 201 arefixed by the screw 103.

In step M9, the pocket hole 102 may be formed in the plate 101. Thepocket hole 102 is formed by cutting off the plate 101 serving as thebase to the middle of its thickness. Then the process advances to stepM11 in FIG. 35B.

In the event that the designer has selected the case the mold should befixed by the cut-off holes and screws in step M7, then in step M10 thecut-off holes may be formed. The cut-off holes may be formed by cuttingthe base parts off so as to pass through it. Thereafter, in step M11 inFIG. 35B, clearance (designation) and depth of the fixing screws areinput. In step M12, the number and location of the fixing screws areinput.

In step M13, tapped holes may be formed in the screw parts to be fixedto the plate, and in step M14 spot facing holes for the fixing screwsmay be formed. The spot facing holes may be formed in the plate locatedbeneath the mold. The process then advances to step M19.

If the designer has not selected the screw clamping by way of the pocketholes or the cut off holes in step M7, then the process goes to stepM15. For example, there is a case where the designer intends to fix thenest shown in FIG. 37A in the block. In FIG. 37A, a reference 201denotes a block having the pocket holes (spot facing holes) 203 and thetapped holes therein, and a reference 202 denotes a nest having a tappedhole 205 therein. Now FIG. 37A illustrates the case wherein the nest 202may be put into the spot facing hole in the block 201 and fixed by thescrew from the bottom surface.

In FIG. 37B, a reference 206 signifies a block having a stepped openingportion 207, and a reference 208 signifies a nest having a rib 209. FIG.37B illustrates the case where the nest 208 may be inserted from thebottom surface of the block 206 and then fixed by other plate. The rib209 of the nest 208 cannot be drafted because of its engagement with thestepped opening portion 207.

The cut-off holes for the parts being fixed to the plate 101 serving asthe base may be formed. In step M16, shape and dimension of the rib ofthe nest may be input.

In step M17, ribs may be provided to the nest, etc. In step M18,clearance (relief) for the rib may be formed in the parts serving as thebase. After this, in step M19, it may be checked whether or notsucceeding parts is present. If the succeeding parts has been present(YES), then the process returns to step M5. There the mold base data maybe read out from the base file 12, and steps M6 to M18 may be repeated.Unless the succeeding parts has been present (NO), then the process maybe completed. With the above processes, the mold may be arranged in themold base.

As stated earlier, according to the mold design method according to thetwelfth embodiment, it would be evident that the designer may design thefixing parts by selecting in step M7 any of the fixing parts structuressuch as clamping screw, rib, etc. those being patternized in advance,then displaying the fixing parts in the perspective view of the moldmodel, and then inputting fixing location, nominal designation ofthread, rib dimension etc. via the keyboard. Therefore, the designer mayget the fixing parts structures instead of designing them at thebeginning. As a result, a burden of the designer can be extremelyreduced.

As discussed in the twelfth embodiment, clamping screw, rib, etc. areprepared preliminarily as patternized information of the fixing parts.Thus, it would be evident that, since input items can be decreasedsignificantly, the fixing structures of the mold parts may be designedin a short time and that, even if the designer has little knowledgeconcerning the injection molding, he or she may design the fixingstructures of the mold parts. As a result, such design operation may beconducted effectively.

(13) Thirteenth Embodiment

FIG. 38 is a view showing an image on the display upon designing thegate according to the thirteenth embodiment of the present invention.FIG. 39 is a flowchart illustrating design process of the gate structureaccording to the thirteenth embodiment of the present invention. In thisprocess, the gate used for injecting the resin into the mold may bedesigned in the gate design section 62.

Referring to FIG. 38, the designer may display a mold design menu screenon the display 19 to then select “gate design”. In FIG. 39, in step N1,the designer may first select either the mold design of two-platestructure or the mold design of three-plate structure. In the mold oftwo-plate structure, the runner stripper plate for introducing the resininto the cavity has been omitted. The mold of three-plate structurecomprises the runner stripper plate, the cavity plate, and the coreplate.

If the mold of two-plate structure may be selected (YES), then in stepN2 the top view of the parting plane for splitting the mold may bedisplayed on the display 19. Then the process goes to step N3 where thedesigner may select kinds (type, dimension) of the gate. If the designerhas selected the side gate in step N3 (YES), then in step N4 thedesigner may instruct the gate location. Now, as shown in FIG. 40, theisometric drawing of the core 4 and the moldings 100 may be depicted onthe display 19. In FIG. 40, a reference 301 is a gate which is providedin the core 4. In step N5, a sectional shape and dimension of the gateare input, and in step N6 a geometric locus of the gate may be formed.The gate forming direction is Y direction, as shown in FIG. 40.

In the case of designing the side gate, as shown in FIG. 41A, the gateforming direction may be defined by the composite vector in the X and Ydirections. Default (not arranging direction) is +X direction. A lengthin the (+) direction and a length in the (−) direction are input basedon the parting line. It may be selected by the foregoing menu screen inFIG. 38 whether or not the side gate is provided in either the cavity 3or the core 4.

In step N7, the designer may instruct a groove which is to be impressedon the contacted surface of the cavity and the core. Then a groove maybe formed by sweeping the gate profile along the parting plane.

If the designer has selected a submarine gate in step N3 (NO), then instep N8 the designer may designate a gate location. Then in step N9, adiameter of the gate and a taper thereof may be input. In step N10, aslant angle of the gate may be input. In step N11, the designer mayinstruct a groove which is to be impressed on the contacted surfacebetween the cavity and the core. In the gate design section 62, a groovefor the gate of the circular cone provided on the deepest plane may beformed.

Conversely, if the designer has designed the mold of three-platestructure in step N1 (YES), then in step N12 the designer may designatea gate location. Instruction of the gate location may be input byselecting the foregoing menu screen in FIG. 42. Then in step N13, adiameter of the gate and a taper thereof are input.

In step N14, the designer may read a pin gate (gate bush) having aprofile being closet to the gate profile, for example, from the basefile 12. The gate bush is a mold standard parts, wherein bush holeforming location, spot facing diameter, spot facing depth, holediameter, and hole depth are normalized, as shown in FIG. 41B.

In step N15, the gate bush may be placed on the isometric drawing, etcof the mold. With the above process, side gate, pin gate, etc. forinjecting the resin into the mold may be designed.

In the mold design method according to the thirteenth embodiment, thedesigner may display the selected gate on the perspective view of themold model by selecting in steps N1 or N3 one of the side gate,submarine gate, pin gate, etc. all being patternized previously, so thathe or she may design the gate structure such as gate location, type anddimension of the gate, treatment of the connection portion, etc. via thekeyboard 17. Therefore, the designer may get the gate structures withoutdesigning them at the beginning. As a result, the thirteenth embodimententails such an advantage that a burden of the designer can be extremelyreduced. Furthermore, in the thirteenth embodiment, since variousparameters required for providing the gates are patternized, designoperations may be simplified. In other words, since input items can besignificantly decreased because of patternization of the parameters, thedesigner may design the gates in a short time.

(14) Fourteenth Embodiment

FIG. 43 is a view illustrating an image on the display at the time whenthe runner may be designed according to the fourteenth embodiment of thepresent invention. FIG. 44 illustrates a flowchart for designing therunner according to the fourteenth embodiment of the present invention.In this process, a runner for use in introducing the resin into the moldin the lateral direction will be designed in the runner design section63.

Referring to FIG. 43, the designer may display mold design menu screenon the display 19 to select “runner design”. In FIG. 44, in step O1, thedesigner may select either mold design of two-plate structure or molddesign of three-plate structure. If the designer has selected “molddesign of two-plate structure” (YES), then in step O2 the top view ofthe contacting plane (parting plane) between the cavity and the core maybe displayed on the display 19. Then the process advances to step O4.

On the contrary, if the designer has selected “mold design ofthree-plate structure” in step O2 (NO), then in step O3 the top view ofthe contacting plane (parting plane) between the cavity plate and therunner stripper plate may be displayed on the display 19. Then in stepO4, a runner locus may be formed on the top view of the mold. AS shownin FIG. 45, the runner may be formed in the Y direction succeedingly tothe gate 301. The runner locus may displayed by a straight line.

Thereafter, in step O5, the designer may determine a sectional shape ofthe runner. The runner locus may be determined when the designerdesignate locations of the cavity and the core on the menu screen. Therunner locus may be designed by employing either a method fordesignating the starting point and the end point and then connectingthem or a method for inputting the starting point and incremental value.The sectional shape of the runner may be designated by the designer onthe menu screen.

FIGS. 46A to 46D show the sectional shape and the dimension of therunner. FIG. 46A shows the runner having a rectangular sectional shape.For the rectangular runner, a width and a height may be specified on thebasis of the parting line PL. FIG. 46B shows the runner having atrapezoidal sectional shape. For the trapezoidal runner, upper and lowerbase dimensions and a height may be specified on the basis of theparting line PL. FIG. 46C shows the runner having a semicircularsectional shape. For the semicircular runner, a diameter may bespecified on the basis of the parting line PL. FIG. 46D shows the runnerhaving a circular sectional shape. For the circular runner, a diametermay be specified on the basis of the parting line PL.

If the designer has selected the case the sectional shape of the runnershould be formed as a circular one, then in step O6 a radius of thecircle may be input. If the designer has selected the case the sectionalshape of the runner should be formed as an upward semicircular one, thenin step O7 a radius of the upward semicircle may be input. If thedesigner has selected the case the sectional shape of the runner shouldbe formed as an upward trapezoidal one, then in step O8 the runnerdesign section 63 may input dimensions of the trapezoid. If the designerhas selected the case the sectional shape of the runner should be formedas a downward trapezoidal one, then in step O9 the runner design section63 may input dimensions of the trapezoid. If the designer has selectedthe case the sectional shape of the runner should be formed as adownward semicircular one, then in step O10 the runner design section 63may input a radius of the downward semicircle.

In step O11, the runner sectional shape may be sweeped along the runnerlocus to result in a stereoscopic profile of the runner.

In step O12, the runner design section 63 may attach rotation bodies (½)both having the same sectional shape to edges of the runner. Therotation body signifies a cutting tool for connecting the runner to thegate. ½ denotes a rate at which the cutting tool abuts a cut plane,i.e., a plane to be cut.

In step O13, impression may be performed in compliance with thesectional shape of the runner. In the case of the runner having thecircular sectional shape, in step O14 both sides of the contacting planebetween the cavity and the core may be impressed. The impression may bederived from logical difference in the sweeped runner profile. In thecase of the runner having the upward semicircular sectional shape andthe upward trapezoidal sectional shape, in step O15 the upper side ofthe contacting plane may be impressed. The impression may be derivedfrom logical difference in the sweeped runner profile. In the case ofthe runner having the downward semicircular sectional shape and thedownward trapezoidal sectional shape, in step O16 the lower side of thecontacting plane between the cavity and the core may be impressed. Theimpression may be derived from logical difference in the sweeped runnerprofile. With foregoing processes, the runner for introducing the resininto the mold in the lateral direction has been able to be designed.

In the fashion described above, the mold design method according to thefourteenth embodiment, the designer may display the selected runner asthe perspective view of the mold model on the display 19 by selectingeither the two-plate runner structure or the three-plate runnerstructure, both being preliminarily prepared as patternized information.Then the designer may design the runner structure by selecting runnersectional shape, respective dimensions of runner sectional shape, locus,and process for the connecting portion, and inputting numeral values viathe keyboard 17. Therefore, the designer may attain the runnerstructures without designing them at the beginning. As a result, thefourteenth embodiment may achieve such an advantage that a burden of thedesigner can be extremely reduced.

According to the fourteenth embodiment of the present invention, itwould be understood that, since runner sectional shape of two-plate orthree-plate type, respective dimensions of runner sectional shape,locus, etc. are prepared as patternized information, input items by thedesigner can be significantly reduced, and therefore the designer maydesign the runners in a short time. In addition, the designer havinglittle knowledge about the injection molding may also design therunners.

(15) Fifteenth Embodiment

FIG. 47 is flowchart illustrating design process of the gas ventaccording to the fifteenth embodiment of the present invention. In thisprocess, the gas vent may be designed in the gas vent design section 65to release the air from the cavity portion of the cavity/core when theresin is poured into the mold.

In FIG. 47, in step P1, the top view of the parting plane 200 includingthe product shape, as shown in FIG. 48, is displayed on the display 19.In FIG. 48, a reference 303 denotes an ejector pin hole. The ejector pin(not shown) may be passed through the ejector pin hole 303 when themoldings 1 is drafted.

Next, in step P2, final shot position information as the result of resinsuperplasticized analysis may be read. The resin superplasticizedanalysis denotes a simulation as for the flowing directions (weld lines)taken by the resin when it is injected through the gate previouslydesigned. According to this analysis, arrival points of the resin may beunderstood as the final shot position.

In step P3, the final shot position may be displayed on the display 19so as to be superposed on the top view of the core including the productshape shown in FIG. 48. Then, in step P4, it may be detected whether ornot the resin (weld line) intersects with the parting line. If it hasbeen detected that the resin can be filled in the cavity core normally(YES), then in step P5 intersecting points between the parting line andthe final shot position may be calculated.

In turn, in step P6, the designer may instruct the direction of the gasvent employing the intersecting point as the starting point. In step P7,the designer may instruct the location to which the gas vent isprovided. The gas vent would be located on or beneath the parting line.

In step P8, a width of the gas vent may be input, and in step P9 theresin to be used may be input. Then, in step P10, the designer maydecide a depth of the gas vent based on the resin material database. Forinstance, the designer may designate a depth and a width of the gasvent. In step P11, a gas vent groove may be formed by sweeping thesectional shape (rectangle). The gas vent 304 as shown in FIG. 60 isdisplayed on the top view of the mold base superposedly on the display19. The gas vent 304 may be provided on the location opposing to thegate 301. In FIG. 49A-1, the drawing in broken line circle maycorrespond to a sectional view of the gas vent 304 viewed from I-I′arrow line. In the drawing in broken line circle, a reference a shows adepth of the gas vent, and a reference b shows a width of the gas vent.

Conversely, if it has been detected in step P4 that the resin may notintersect with the parting line (NO), then the process goes to step P12.In case, as the result of the resin superplasticized analysis, it hasbeen found that a void 305 will be caused at the location shown in FIG.49A because of the air being caught in the resin, the resin may notintersect with the parting line.

In step P12, it may be decided whether or not there is an ejector pinhole 303 near the void 305. If it has been decided that the ejector pinhole 303 is present (YES), then the process proceeds to step P15. If ithas been decided that there is no ejector pin hole 303 (NO), then theprocess goes to step P14 where the gas vent design section 65 mayarrange the ejector pin hole 303 in the center of the void 305. Then instep P15, the resin to be used may be input.

Subsequently, in step P16, the designer may select whether or not adimensional tolerance of the ejector pin hole 303 must be expanded. Ifit has been selected that the dimensional tolerance must be expanded(YES), then in step P17 where the designer may determine a maximum gapfrom the resin material database. The dimensional tolerance will beexplained in the nineteenth embodiment. In step P18, the dimensionaltolerance of the ejector pin hole 303 may be changed to a range between+0 and −maximum gap.

Here drawings of the ejector pin hole 303 before and aftermagnification, as shown in FIG. 49B, are depicted on the display 19. InFIG. 49B, ±D is a diameter of the ejector pin hole 303. If the gapshould be expanded, φD+0.01 to φD+0.03 would be calculated.

If the designer has selected in step P16 that, in place of expansion ofthe dimensional tolerance, an air vent dovetail as shown in FIG. 49Cmust be provided on the periphery of the ejector pin 306 (NO), then instep P19 a depth of the dovetail may be decided based on the resinmaterial database. In step P20, the number of the dovetail may bedetermined. For purposes of example, in FIG. 49C, a depth of thedovetail has been set within 0.02 to 0.04 mm, and the number of thedovetail has been set to be four.

In step P21, a length of the dovetail may be input. After this, in stepP22, the gas vent may be formed by sweeping the sectional shape(semicircle). With these processes, the gas vent 304 may be designedwhich serves to release the air from the space (cavity) portions of thecavity and the core when the resin is forced to be poured into the mold.

As has been discussed earlier, according to the mold design methodaccording to the fifteenth embodiment, it would be understood that thegas vent 304 for releasing the gas has been arranged at the locationwhere the resin reaches finally in step P3, based on the result of theresin superplasticized analysis being superposed on the perspective viewof the mold. Therefore, the designer may arrange the gas vent 304 at thelocation suitable for the resin which being poured into the cavityportion of the mold block 100 without regard to experience andperception of the designer. Besides, it would be clear that, since thefinal shot position of the resin may be calculated by way of thesuperplasticized analysis CAE (Computer-Aided Engineering), the designermay design the gas vent structure without knowledge of the injectionmolding resin.

According to the fifteenth embodiment of the present invention, itshould be noted that, if the method has been adopted wherein the gas isreleased by employing the ejector pin 306, correction operations such aslocation modification of the ejector pin 306, provision of the dovetailin the ejector pin 306, and dimension modification of the ejector pin306 may be applicable.

In case, from the result of the resin superplasticized analysis, it hasbeen seen that the resin cannot reach the gas vent 304 so that the gasstays in the cavity portion of the mold block 100 to produce the void305, the gas vent design employing the ejector pin 306 may be adopted.Since a tolerable clearance (width, depth, etc.) may be displayed on thedisplay 19, the designer may design the gas vent 304 by inputtingnecessary dimensions via the keyboard 17.

Therefore, it is of course that the designer may attain the runnerstructures without designing them at the beginning. As a result, thefourteenth embodiment may achieve such an advantage that a burden of thedesigner can be extremely reduced.

According to the fifteenth embodiment of the present invention, it wouldbe evident that, if the designer designates shape and specification ofthe gas vent 304 prepared previously as patternized information via thekeyboard 17, the profile of the designated gas vent 304 may be arrangedin the mold model. Therefore, the designer may obtain the gas ventstructures without designing the gas vent 304 at the beginning, and thata burden of the designer can be extremely reduced. In addition, it wouldbe apparent that, since required parameters are patternized,simplification of operations can be achieved and, since input itemsinput by the designer can be significantly reduced, the designer maydesign the gas vent 304 in a short time.

(16) Sixteenth Embodiment

FIGS. 50 and 51 are views for illustrating images of the display whenthe ejector pin being designed according to the sixteenth embodiment ofthe present invention. FIG. 52 is a flowchart illustrating designprocess of the ejector pin according to the sixteenth embodiment of thepresent invention. In this process, the ejector pin may be designed inthe ejector pin design section 66.

Referring to FIG. 50, first the designer may select “ejector pin design”from mold design menu screen displayed on the display 19. In step Q1,the cavity/core data D4 are read out, and in step Q2 the top view of thecore may be displayed on the display 19. In step Q3, position of theejector pin 306 may be displayed on the display 19.

In the next, in step Q4, the designer may select a sectional profile ofthe ejector pin 306. If the ejector pin formed of a round pin has beenselected (YES), “hole design for round pin” may be selected on the menuscreen shown in FIG. 51. So a hole for round pin shown in FIG. 41C maybe formed. The designer may arrange the hole for round pin on the basisof the bottom surface of the plate. In addition, the designer maydesignate minimum hole depth, hole diameter, hole diameter+1 (where 1 isrelief, i.e., clearance) of the hole for round pin. In step Q5, adiameter of the pin may be input, and the process advances to step Q7.

If the designer has selected a square pin in step Q4 (NO), “hole designfor square pin” may be selected on the menu screen shown in FIG. 51. Instep Q6, a pin diameter may be input. Here a hole for square pin shownin FIG. 41D may be displayed on the display 19. The designer may arrangethe hole for square pin on the basis of the bottom surface of the plate.In addition, the designer may designate minimum hole depth, square holedimensions (X, Y), square hole dimensions+1 (where 1 is nominal size) ofthe hole for square pin.

In step Q7, a length of a slider portion of the ejector pin 306 may beinput, and then in step Q7 a stroke of the ejector pin 306 may be input.Next, in step Q9, appropriate ejector pin 306 will be read from the basefile 12. The ejector pin 306 has been stored in the database as a moldstandard parts. In step Q10, the pin design section 66 may input aclearance of the pin.

Subsequently, in step Q11, a hole may be formed in the feed-throughparts. As shown in FIG. 53, the ejector pin 306 and the ejector pin hole303 are displayed on the display 19 so as to overlap with the top viewof the product shape.

The pin holes 303 must be opened in nest of the core 4, movable moldplate (core plate), movable support plate, and upper ejector plate.

In step Q12, it will be checked whether or not design of the ejector pin306 has been finished. If design of the ejector pin 306 has not beenfinished (NO), the process returns to step Q3 to repeat steps Q3 to Q11once more. If design of the ejector pin 306 has been finished in stepQ12 (YES), the process may be completed. With this process, the ejectorpin be able to be designed.

In this manner, according to the injection mold design method of thesixteenth embodiment, it would be obvious that, by selecting in step Q4any of the structure such as sectional shape, dimension, length of slideportion, etc. of the ejector pin, all being stored as patternizedinformation, the designer may display selected ejector pin on theperspective view of the mold model on the display 19. It would beapparent that, since the designer may design the ejector pin 306 bydesignating location, dimension, shape, etc. and inputting numerals viathe keyboard 17, he or she may obtain the ejector pin structures withoutdesigning the ejector pin structure at the beginning, and that a burdenof the designer can be extremely reduced. Since kinds of the ejector pin306 such as round pin, square pin, straight pin, stepped pin serving asparameters have been prepared as patternized information preliminarily,operation can be simplified. In addition, since the input items can bereduced extremely because of patternized information, the ejector pin306 can be designed in a short time.

(17) Seventeenth Embodiment

FIG. 54 is a view showing an image when designing the cooling pathaccording to the seventeenth embodiment of the present invention. FIG.55 is the isometric drawing of the mold when designing the cooling pathaccording to the seventeenth embodiment of the present invention. Inthis process, the cooling path for cooling the mold may be designed inthe temperature adjusting structure designing section 67.

FIG. 54 shows a menu screen displayed on the display 19. The designermay select “8. cooling path design” from this menu screen. On the menuscreen, selection item for formation/deletion of the cooling path,designation item for the cooling path forming plane, input item for thehole diameter of the cooling path, input item for configuration (layout)coordinate are displayed. On the display 19, the X Z flat plane (frontplane) and Y Z flat plane (side plane) of the cooling path designated bythe designer may be two-dimensionally displayed, hole diameter of thecooling path may be displayed as numerical values, configurationcoordinate of the cooling path may be displayed as numerical values, andso forth. FIG. 55 shows the cooling path three-dimensionally in the moldblock in which the mold is included. In the seventeenth embodiment, twocooling paths are provided in the core 4.

In FIG. 54, the designer may first display the mold design menu screenon the display 19, and then select “cooling path design”.

Then, the isometric drawing of the mold consisting of the cavity 3 andthe core 4 as shown in FIG. 55 may be displayed on the display 19. InFIG. 55, cooling pipes 308 may cool the mold upon forming the resin.

In the temperature adjusting structure designing section (abbreviatedsimply as “temperature adjusting section” hereinafter) 67, a flat planeon which the cooling pipes 308 are arranged may be determined accordingto instruction of the designer. The flat plane may be set as the X Yflat plane during designing the cooling path. The designer may arrangethe cooling pipes 308 on the designated position. At this time, thedesigner may designate hole diameter of the cooling pipes 308. In theseventeenth embodiment of the present invention, plural positions may bedesignated continuously. If a “cancel” button of the menu screen ispushed, then position designation has been completed.

In this fashion, according to the mold design method of the seventeenthembodiment, it would be obvious that, by selecting either structure ofthe cooling pipes 308 stored as patternized information preliminarily,the designer may display the selected cooling pipes 308 on theperspective view of the mold model on the display 19. It should be notedthat, since the structure design of the cooling pipes 308 may befacilitated if the designer inputs numerical values such as holediameter, position, PT screw nominal size via the keyboard 17, thedesigner may obtain the structure of the cooling pipes 308 withoutdesigning the cooling pipe structure at the beginning, and that a burdenof the designer can be extremely reduced. Since required parameters havebeen prepared as patternized information preliminarily, design operationcan be simplified. Furthermore, since the input items can be reducedextremely because of patternized information, the cooling pipe 308 canbe designed in a short time.

(18) Eighteenth Embodiment

FIGS. 56A and 56B shows a sectional view of the mold when designing alink structure of three-plate type according to the eighteenthembodiment of the present invention. In FIG. 56A, a reference 401denotes a fixing side clamping plate constituting a main body of theinjection mold machine; 5, runner stripper plate in which the runner isprovided; 3A, cavity plate in which the cavity is provided; and 4A, coreplate in which the core is provided. These plate structure may bepatternized in advance.

First the designer may select the mold opening control structure fromthe menu screen displayed on the display 19. For the mold openingcontrol structure, the link, puller bolt, etc. have been prepared aspatternized information. As shown in FIG. 56A, the display 19 maydisplay the fixing side clamping plate 401, the runner stripper plate 5,the cavity plate 3A, and the core plate 4A. Next, the designer may inputnecessary dimensions such as positions of the plates 5, 3A and 4A, aseparating distance between the plate 5 and the plate 3A, a separatingdistance between the plate 3A and the plate 4A, etc. via the keyboard17.

Next, in FIG. 56B, it may be checked whether or not interference residesbetween the link (coupling portion) and plates (i.e., whether they maycontact with each other or not). A reference 402 denotes a link whichmay couple these three plates. As shown in FIG. 56B, the display 19 maydisplay the view in which the fixing side clamping plate 401, the runnerstripper plate 5, the cavity plate 3A, and the core plate 4A are stackedand three plates 5, 3A and 4A are coupled by the link.

The designer may check whether or not clearance is created between thefixing side clamping plate 401 and the link 402. This clearance must bechecked to confirm whether or not the link 402 and the fixing sideclamping plate 401 can be combined with each other without mutualengagement when three plates 5, 3A and 4A are clamped to the mold. Ifthere has been no clearance between them, warning, interference, etc.would be displayed on the display 19. With watching the screen on thedisplay 19, the designer may correct them.

As discussed earlier, according to the mold design method of theeighteenth embodiment of the present invention, it would be obviousthat, when the designer select any one of structures of the link 402being patternized preliminarily and stored in the storing means, thedisplay 19 may display the selected link 402 on the perspective view ofthe mold model. Also, by inputting the separating distances betweenrespective plates 5, 3A and 4A via the keyboard 17, the designer maycheck whether or not clearance has been created between the fixing sideclamping plate 401 and the link 402.

Accordingly, it would be evident that, since the designer may effectstructure design of the link structure 402 merely by inputtingseparating distances required for mold opening in the injection moldingmachine, he or she may obtain the link structures without designing thelink structure at the beginning, and that a burden of the designer canbe extremely reduced. The designer may design the link structures unlesshe or she knows mold opening operation as to three-plate type structurewell. It would also be evident that, since the mold opening structurehave been prepared as patternized information preliminarily, the inputitems can be reduced extremely, and that the three-plate type link canbe designed in a short time.

(19) Nineteenth Embodiment

FIG. 57 is a view showing dimensions of parts having dimensionaltolerance according to the nineteenth embodiment of the presentinvention. In the nineteenth embodiment of the present invention, if thedimensional tolerances have already been decided between parts of themold model, as shown in FIG. 57, half tolerance of the dimension ofgiven parts may automatically modified to central tolerance. By way ofexample, as shown in {circle around (1)} of FIG. 57, the display 19 maydisplay a dimension 50 as a width of the parts, and also display anupper limit +0 and a lower limit −0.2 like “50+2−0.2” as half tolerancetherefor. As for a height of the parts, it may display an upper limit+0.1 and a lower limit −0 like “5+0.1−0” as half tolerance for a heightof 5. The product shape is displayed by central values.

In the nineteenth embodiment of the present invention, as shown in{circle around (2)} of FIG. 57, the designer may switch the display intocentral tolerance via the keyboard 17. In this event, as shown in FIG.57, the display 19 may change the width 50, upper limit +0, and lowerlimit −0.2 of the parts into 49.9±0.1. With regard to the parts havingthe height 5, upper limit +0.1 and lower limit −0, the display may bechanged into 5.05±0.05. Now a dimension ε may be displayed as α±δ. Acentral value ε is ε=α+[(β+γ)/2], and an error δ is δ=[(β−γ)/2] and δ>0.The half tolerance is also referred to as modification directiontolerance.

Besides, in the nineteenth embodiment of the present invention, as shownin {circle around (3)} of FIG. 57, the screen on the display may bechanged to designer's objective dimension (working target dimension) byvarying the central tolerance of the dimension of the parts into thehalf tolerance. The width of the parts of 49.9±0.1 may be modified to49.95. The height of the parts of 5.05±0.05 may also be modified to5.075. Thus, as shown in FIG. 57, correct allowance may be provided inthe directions A and B. Where the working target dimension η may bedisplayed like η=ε+δ·κ. κ is a parameter for the target dimension. Inthe nineteenth embodiment, κ=+½ may be applied.

If the dimensional tolerance has been fixed between the parts of themold model, the designer may select either the central tolerance or thehalf tolerance for the dimensions of the given parts. Thus, based on thecentral tolerance or the half tolerance, the display 19 may displaymodified dimensional tolerance between the parts of the mold model.

As mentioned above, in the mold design method of the nineteenthembodiment of the present invention, if the mold dimensions and theparts dimensions have been given in terms of the half tolerance, thedisplay 19 may display the central tolerance being modified from thehalf tolerance in accordance with instruction of the designer.Therefore, the designer can confirm target working dimensions of theintended mold or the intended parts on the screen.

Further, in the mold design method of the nineteenth embodiment of thepresent invention, even if the mold dimensions and the parts dimensionshave been given by means of the central tolerance, the display 19 maydisplay the half tolerance being modified from the central tolerance inaccordance with instruction of the designer. Therefore, the designer canchange target working dimensions of intended mold or parts on thescreen. As a result, the dimensions may be modified in the direction towhich correct allowance has been permitted and within limit tolerance.

According to the nineteenth embodiment of the present invention, in theevent that the designer has selected either the central tolerance or thehalf tolerance for the dimensions of the given parts via the keyboard17, the display 19 may display modified dimensional tolerance betweenthe parts of the mold model based on the central tolerance or the halftolerance. Therefore, it would be apparent that the designer can edittarget working dimensions of intended mold or parts on the screen. Thus,artificial error due to missing of the dimensional tolerance, etc. canbe eliminated. The mold can be designed with considering the dimensionaltolerance.

In the first to nineteenth embodiments of the present invention,although the methods for designing the mold by reading individual datahave been explained, another method for designing the mold by readingdata groups to which attributes (names) are assigned respectively willbe explained in the twenty-seventh embodiment.

(20) Twentieth Embodiment

FIGS. 58 to 60 are views illustrating a design item system of the molddesign system according to the twentieth embodiment of the presentinvention. In the twentieth embodiment, mold design items are registeredpreliminarily in the design system to effect the mold design readily andquickly.

In FIG. 58, a reference 22 denotes mold design items. The mold designitems 22 are stored in the other memory 21 and are classified roughlyinto three groups. A reference 23 denotes product shape correctionitems. The correction items 23 are registered contents of preliminarybetween the mold designer and the mold designer to be conducted at thetime when the construction of the mold is started. The contents ofcorrection items are, for example, determination of mold openingdirection, provision of draft slope to the product, detection ofundercut, definition of the parting line, design of the gate, and filemanagement.

The following will be the design items. The mold opening direction maybe decided to “Z direction” in which the product is released from thecore. The draft slope may be provided to facilitate release of theproduct from the core. Since the undercut prevents releasability of theproduct, the core must be formed as the nest structure. The parting lineis formed to obtain the parting plane for splitting the mold block intothe cavity and the core. The gate is provided to inject the resin intothe cavity portion between the cavity and the core. Product shapecorrection data being derived by correcting the product shape incompliance with the product shape correction items 23 are stored in thework memory 13 and then managed.

In FIG. 59A, a reference 24 denotes mold design items. The mold designitems 24 for the mold designer's exclusive use are, for example,correction of molding shrinkage rate, formation of cavity/core block,determination of mold base, formation of the parting plane, design ofgate, runner, and sprue, design of mold temperature adjusting waterpath, design of ejector pin, check of hole interference, split of neststructure, design of slide core, and file management.

The design contents are as follows. In order to improve releasability ofthe product, the cavity and the core of the mold may be designed bymodifying the dimensions according to shrinkage rate of the product. Thecavity and the core may be designed by splitting the mold block by meansof the parting plane. The mold base may be designed by selecting plates,to which the cavity and the core being fixed, and their fixing parts.The parting plane may be designed by selecting the parting line. Thegate, runner, and sprue, these constituting resin flowing route, may bedesigned by selecting respective sectional shapes according to viscosityof the resin. The mold temperature adjusting water path (cooling waterpath) may be designed by considering other hole profiles.

The ejector pin may be designed by checking interference with the moldtemperature adjusting water path. The undercut portion of the productmay be formed by splitting the core into nests. The nest parts may bedesigned slidably in the X direction or Y direction.

In FIG. 59B, a reference 25 denotes manufacturing model forming items.The forming items are incorporated for use in the mold designer and themold manufacturer. The contents of the forming items are electricdischarge machining electrode design, file management, and the like. Theelectric discharge machining electrodes are manufacturing jigs formachining the inner surface of the cavity. In order to round the edge ofthe moldings, the inner edge of the cavity may be worked to form thecircular cylinder surface by the manufacturing jigs. Working data (NCdata) used to fabricate the electrodes may be stored in the work memory13 and then managed. Note that these design items may be stored in thememory 21 shown in FIG. 2. On starting the design system, these designitems may be displayed on the display 19 shown in FIG. 2.

FIG. 60 illustrates classification of the design items in the molddesign system. In FIG. 60, the product designer may design the productshape to be molded by the injection mold. In compliance with the productshape correction items 23 of the mold design system, the productdesigner may effect determination of the mold opening direction,provision of the draft slope to the product, detection of the undercutportion, definition of the parting line, design of the gate, and filemanagement. The product designer may offer the product shape correctiondata to the mold designer. Note that the product shape correctionoperation may be executed by the mold designer.

In turn, according to the mold design items 24, the mold designer mayeffect, for example, correction of molding shrinkage rate, formation ofcavity/core block, determination of mold base, formation of the partingplane, design of gate, runner and sprue, design of mold temperatureadjusting water path, design of ejector pin, check of hole interference,split of nest structure, design of slide core, and file management. Themold designer may offer the mold parts data to the mold manufacturer.Then, according to the manufacturing model forming items 25, the moldmanufacturer may execute electric discharge machining electrode design,file management, etc. It should be noted that manufacturing modelformation may be done by the mold designer.

As described above, according to the design item system of the molddesign system according to the twentieth embodiment of the presentinvention, the design items of the mold have been roughly classifiedinto three categories, i.e., product shape correction items, mold designitems, and manufacturing model formation items, and then registered inthe system.

Therefore, determination of the mold opening direction, provision of thedraft slope, detection of the undercut portion, definition of theparting line, gate design, etc. may be effected in compliance with theproduct shape correction items, i.e., the contents of preliminarybetween the product designer and the mold designer conducted whenstarting construction of the mold.

Furthermore, correction of molding shrinkage rate, formation ofcavity/core block, determination of mold base, formation of the partingplane, design of gate, runner and sprue, design of mold temperatureadjusting water path, design of ejector pin, check of hole interference,split of nest structure, design of slide core, etc. may be effected incompliance with the mold design items being incorporated for use in themold designer only.

Moreover, design of the electric discharge electrodes may be effected incompliance with the manufacturing model formation items beingincorporated for use in the mold designer and the mold manufacturer. Inthat case, since software resources of the system can be commonly usedby the product designer, the mold designer, and the mold manufacturer,design of the mold can be done easily and quickly. Preliminary andtransfer of the product shape data can be effected smoothly whendesigning the mold, and processes required for the designers from theproduct design to the mold design can be reduced. A design method of themanufacturing jigs of the mold parts will be explained in thetwenty-ninth embodiment.

(21) Twenty-First Embodiment

FIG. 61 is a flowchart illustrating detection process of the undercutportion of the product according to the twenty-first embodiment of thepresent invention. FIGS. 62A to 62C, 63A and 63B are views illustratingsupplementary explanations. In the twenty-first embodiment, as shown inFIG. 62A, detection of the undercut portion of the product shape 26having two eaves shapes will be explained. In FIG. 62A, a reference 26Adenotes a first eaves shape which extends from one side of the productshape 26 laterally, and a reference 26B denotes a second eaves shapewhich is formed beneath the first eaves shape 26A. It may be detectedwhether or not the portion existing between two eaves shapes 26A and 26Bfunctions as the undercut portion 26C.

In FIG. 61, in step R1, the designer may first select one of planesconstituting the product shape 26. For example, an upper plane of theeaves profile 26A as shown in FIG. 62B may be selected. In FIG. 62B, thedisplay 19 may display a lattice-like image of the selected plane on thescreen.

In step R2, the parting line forming section 41 may form dot lines onthe upper surface of the eaves shape 26A. It is preferable that pluraldot lines are prepared. For instance, the dot lines may be formed on theintersecting points of the lattice. In the sectional view of the productshape 26 in FIG. 62C, a X mark is the location of the dot lines and, forpurposes of simplicity in the explanation, only one point isillustrated. Then, in step R3, the parting line forming section 41 mayproject the dot lines on the plane of the eaves profile 26A in the +Zdirection. In FIG. 62C, a black round mark is the projected location inthe +Z direction.

In step R4, the parting line forming section 41 may detect whether oneor more dot lines can be projected onto other planes or not. In theexample in FIG. 62C, dots are projected onto respective edges of upperand lower portions of the eaves profile 26B (two-point projection). Ifno dot line can be projected on other planes in step R4 (NO), then theprocess proceeds to step R8. On the contrary, if one or more dot linescan be projected onto other planes in step R4 (YES), then the processadvances to step R5.

In step R5, the parting line forming section 41 may project the dotlines on the plane of the eaves profile 26A in the −Z direction. In theexample in FIG. 62C, a white round mark is the projected location in the−Z direction. In step R6, the parting line forming section 41 may detectwhether one or more dot lines can be projected onto other planes or not.In the example in FIG. 62C, dots are projected onto an edge of the lowerportion of the eaves profile 26A (one-point projection).

If no dot line can be projected on other planes in step R6 (NO), thenthe process proceeds to step R8. Conversely, if one or more dot linescan be projected onto other planes in step R6 (YES), then the processadvances to step R7.

In step R7, the plane may be stored as the plane constituting theundercut portion 26C in the work memory 13.

In step R8, the designer may decide whether or not detection of theundercut has been completed with respect to all planes. Unless detectionof the undercut has been completed in step R8 (NO), the process returnsto step R1 where one plane may be selected. Subsequently, steps P2 to P8are repeated once again.

By way of example, the upper plane of the eaves profile 26B as shown inFIG. 63A has been selected in step R1. In FIG. 63A, the display 19 hasdisplayed the lattice-like image of the selected plane on the screen.

In step R2, the parting line forming section 41 may form dot lines onthe upper surface of the eaves shape 26B. In FIG. 63B, a × mark is thelocation of the dot lines and, for purposes of clarification of theexplanation, only one point is illustrated. In this example, there isshown the case wherein dots are projected onto e lower edge of the eavesprofile 26B and upper and lower edges of the eaves profile 26A(three-point projection).

Then, in step R3, the parting line forming section 41 may project thedot lines on the plane of the eaves profile 26B in the +Z direction. Instep R4, the parting line forming section 41 may detect whether one ormore dot lines can be projected onto other planes or not. In the examplein FIG. 63A, since there is no projection plane, dots on the plane ofthe eaves profile 26B cannot be projected in the +Z direction(zero-point projection). If no dot line can be projected on other planesin step R4 (NO), then the process proceeds to step R8.

If detection of the undercut has been completed with respect to allplanes in step R8 (YES), then the process advances to step R9 whereconstituting plane of the undercut portion may highlighted on the screenof the display 19.

According to the method for detecting the undercut portion of theproduct shape according to the twenty-first embodiment of the presentinvention, it would be obvious that, by forming dot lines on theconstituting plane of the product and detecting whether or not these dotlines can be projected onto other plane located in the ±Z direction, theundercut portion can be detected easily and in a short time in contrastto the seventh embodiment of the present invention.

(22) Twenty-Second Embodiment

FIG. 64 is a flowchart illustrating extraction process of the partingline according to the twenty-second embodiment of the present invention.FIGS. 65A, 65B and 66A to 66D are views illustrating supplementaryexplanations. In the twenty-second embodiment, an extracting function ofthe parting line is simplfied rather than the first embodiment.

In FIG. 64, in step S1, the designer may first display a profile of theproduct shape 27 along the +Z direction on the screen of the display 19.FIG. 65A is a perspective view showing the product shape 27 of theplastics, and FIG. 65B is a view showing the product shape 27 viewedfrom the mold opening direction (+Z direction). Incidentally, since rearedges of the product shape 27 are obstructive to extraction of theparting line, profile data concerning the rear edges have been unloadedin the memory.

In step S2, the parting line forming section 41 may resolve visibleedges of the product shape 27 and the profile lines (edges) intoelements. In the example in FIG. 65B, an outermost peripheral profileline and edges of the product shape 27 are resolved into straight line,circular arc, etc. (referred to as “line element” hereinafter).

Next, in step S3, the parting line forming section 41 may detect a lineelement having maximum value in the horizontal direction (X direction)of the display screen according to instruction of the designer. This isbecause extraction candidates of the parting lines must be narrowed tosome extent by retrieving the line elements roughly. Detected lineelements may be stored in the work memory 13. In step S4, the partingline forming section 41 may detect other line elements being adjacent tothe line elements having the maximum value in the X direction. At thistime, the display 19 may display the perspective view of the productshape 27, as shown in FIG. 66A. Then, profile data relating to rearedges may be read out from the work memory 13, and the parting line isdisplayed superposedly on the perspective view of the product shape 27.Other line elements being adjacent to the line elements having themaximum value in the X direction may be stored in the work memory 13 asthe candidates of the parting line.

In step S5, depending upon the cases wherein there is no other lineelement adjacent to the line element and wherein two line elements ormore are present as shown in FIG. 66C, the designer may provideinstruction to the system via the keyboard 17. According to the contentsof instruction, in case there has been no other line element adjacent tothe line element, the process goes to step S6 where the line elementsare formed manually. Alternatively, in case there have been two lineelements (1), (2) being adjacent to the line element as shown in FIG.66C, then the process advances to step S7 where the designer may selecteither line element (1) or line element (2) manually. As shown in FIG.66B, in case there has been one other line element being adjacent to theline element, the process proceeds to step S8.

In step S8, the system may store other line element being adjacent tothe line element in the work memory 13 as the candidates of the partingline. In step S9, it may be detected whether or not the line elementshaving the maximum value in the X direction have been detected asadjacent curves, i.e., the line elements have formed a closed loop.

Unless the line elements have formed the closed loop in step S9 (NO),the process returns to step S5. Until the line elements can form theclosed loop, then steps S5 to S8 are repeated.

If the line elements have formed the closed loop in step S9, that is,the line elements having the maximum value in the X direction have beendetected as adjacent curves (YES), the process goes to step S10 wherethe line elements may be extracted as the parting line. In FIG. 66C, theparting line of the product shape 27 is shown by the solid line.

According to the extraction method of the parting line of thetwenty-second embodiment of the present invention, by retrieving theline elements having the maximum value in the X direction of the productshape viewed from the mold opening direction in step S3, extractioncandidates of the parting line have been selected to some extent.

Therefore, it would be evident that the parting line can be extracted ina short time rather than the first embodiment and that in addition theparting line can be extracted in an extremely short time in comparisonwith the conventional case wherein the parting lines are extracted fromthe two-dimensional drawing.

(23) Twenty-Third Embodimnet

FIGS. 67A and 67B are flowcharts illustrating formation process of theparting plane according to the twenty-third embodiment of the presentinvention. FIGS. 68A to 68E are views for use in supplementaryexplanations. Unlike the ninth embodiment, in the the twenty-thirdembodiment, a falt surface, a circular cylinder surface, a circular conesurface, and a free-form surface may be extracted correspondingly towhether or not the parting line is on the same flat surface, and thenthe parting plane can be formed by connecting these surfaces mutually.Note that the mold split section 52 may also have this function.

In FIG. 67A, in step T1, the system may first two adjacent parting linesi, j from n (n=1, 2, 3, . . . i, j, k . . . n) parting lines accordingto instruction of the designer. In the present embodiment, it isregarded that, when both the parting line surrounding an outside of acertain region and the parting line surrounding an inside of the certainregion can exist, the region may constitute the flat surface.

In step T2, it is detected whether or not two adjacent parting lines i,j are on the same flat surface. The detection condition is at this timewhether or not two end points constituting a starting point and an endpoint of the two parting lines i, j and one connecting point are on thesame flat surface. If two parting lines i, j are on the same flatsurface, e.g., the flat surface N as shown in FIG. 68B (YES), then theprocess goes to step T3. In step T3, it may be detected whether or notthe parting line k adjacent to the parting line j is on the same flatsurface. If two parting lines j, k are on the same flat surface N (YES),then the process proceeds to step T8. Unless two parting lines j, k areon the same flat surface N (NO), then the process proceeds to step T4where two parting lines j, k are stored as elements of the flat surfaceN.

Conversely, unless two parting lines i, j are on the same flat surfacein step T2 (NO), then the process goes to step T5 where the parting linei is stored as an unconfirmed element. In the example in FIG. 68B, theparting line adjacent to the flat surface N of the product shape 28 isthe unconfirmed element. Thereafter, this will be stored as the lineelement of the flat surface N+2.

In step T6, it may be detected whether or not the parting line kadjacent to the parting line j is on the same flat surface. If twoparting lines j, k are on the same flat surface N in step T6 (YES), thenthe process proceeds to step T8. Unless two parting lines j, k are onthe same flat surface N (NO), then the process proceeds to step T4 wheretwo parting lines j, k are stored as elements of the flat surface N+1.

In step T8, it may be detected whether or not the last parting line nand the first parting line 1 are on the same flat surface. If the lastparting line n and the first parting line 1 have not been on the sameflat surface (NO), then the process returns to step T1. Two adjacentparting lines i, j may be selected, thereafter steps T2 to T8 arerepeated. If the last parting line n and the first parting line 1 havebeen on the same flat surface in step T8 (NO), then the process advancesto step T9. Where it may be decided whether or not all flat surfacesincluding the parting line have been detected. If entire flat surfaceshave been detected (YES), then the process advances to step T10. Unlessentire flat surfaces have been detected (NO), then the process returnsto step T1. Two adjacent parting lines i, j may be selected, then stepsT2 to T8 are repeated. As a result, all flat surfaces including theparting line have been detected.

In step T10, the designer may detect line elements adjacent to the flatsurface N+1 of the product from unconfirmed elements while watching theproduct shape. This detection of the line elements would be done toconfirm presence of the flat surface adjacent to the flat surface N+1.In case all flat surfaces have been detected in steps T2 to T8, the lineelement being adjacent to the flat surface N+1 is any of circularcylinder surface, circular cone surface and free-form surface.

In step T11, the designer may first detect the circular cylinder surfaceand the circular cone surface from remaining unconfirmed elements. Thecircular cylinder surface and the circular cone surface can be found inthe corner portions where inner surfaces of the product shape 28intersect with each other. In step T12, other unconfirmed elements mayas regarded as elements of sweep surfaces (free-form surfaces). In FIG.68C, a reference 28A denotes a sweep surface of the product shape 28.This surface is a portion where the profile of the core must be finishedto the sweep surface.

In step T13, a borderline on which two adjacent surfaces intersect witheach other (referred to as “intersecting line” hereinafter) may bedetected. In the example in FIG. 68D, the intersecting line of theproduct shape 28 can be found on the portion where the flat surface Nand the flat surface N+1 intersect with each other. If the intersectingline can be detected, interference between the flat surfaces can beprevented.

Subsequently, in step T14, the surfaces may be connected and thentrimmed. In the example in FIG. 68D, the flat surface N and the flatsurface N+2 are connected. In addition, the flat surface N+2 and thecircular cylinder surface are connected.

In step T15, trimmed surface has been determined as the parting plane ofthe product shape 28. FIG. 68E shows the parting plane of the productshape 28. In FIG. 68E, the parting plane of the product shape 28 can beformed by connecting flat surfaces N, N+1, N+4, flat surfaces N+2, N+3modified by the circular cylinder surface, and the sweep surface N+5. Ifthe parting plane has been determined, the mold block 29 may be split bythis parting plane, like the ninth embodiment. Consequently, the cavityblock and the core block may be designed.

As discussed above, according to forming method of the parting planeaccording to the twenty-third embodiment of the present invention, afalt surface, a circular cylinder surface, a circular cone surface, anda free-form surface may be extracted by detecting whether or not theparting line is on the same flat surface, and then the parting plane canbe formed by connecting these surfaces mutually.

Therefore, the parting plane of the product shape 28 can be formedreadily without projecting the main parting line onto the mold blockafter the main parting line being extended in the X, Y directions likethe ninthe embodiment.

(24) Twenty-Fourth Embodiment

FIG. 69 is a flowchart illustrating design process of the ejector pinaccording to the twenty-fourth embodiment of the present invention.FIGS. 70A to 70D are views for use in supplementary explanations. Unlikethe above sixteenth embodiment, in the twenty-fourth embodiment, theejector pin design section may calculate a height of the ejector pinwhen the designer designates the location of the ejector pin.

In FIG. 69, in step U1, the designer may first input design dimensionsof the ejector pin. Such design dimensions of the ejector pin are inputinto the design system via the keyboard 17. At that time, a menu screenas shown in FIG. 70A appears on the display 19. Unlike the image viewbeing explained in the sixteenth embodiment, the hole profile of theejector pin and instruction boxes in which dimensional values are inputare displayed in this one menu screen. The designer may input respectivedimensional values into the instruction boxes. The dimensional valuesare ejector pin hole diameter, relief hole diameter, guide length, ribdiameter, and so on. The rib serves as a disengage-preventing jig whichis provided on the lower end of the ejector pin.

In step U2, the display 19 may display the profile of the core blockviewed along the +Z direction in accordance with instruction of thedesigner. In step U3, the designer may designate the location of theejector pin on the screen of the display 19. In the example in FIG. 70B,a black round mark on the core block 30 means the pin hole. The ejectorpin design section 66 may then detect the pin location coordinates X, Y.The pin location coordinates X, Y are defined by distances from thecenter of the mold.

The display 19 may display the pin location coordinates X, Y in theinstruction window. It is of course that the designer may correct thesevalues via the keyboard 17.

Thereafter, in step U4, the ejector pin design section 66 may then forma circle with the pin designated location as the center. In step U5, thecircle may be projected onto the mold parts. The mold parts are, forexample, core block 30, core plate (not shown), support plate, upperejector plate, and the like. There an assumption is needed that designof the mold base has been completed at this time.

In step U6, the ejector pin design section 66 may then detect a minimumheight and a maximum height of the ejector pin. The height of the pin isdifferent according to the surface profile of the product. For purposesof example, if the surface of the product is slant, the top end of theejector pin must be worked to be slant, so that the ejector pin has theminimum height and the maximum height. In FIG. 70C, a black round markis the maximum height of the ejector pin, while a black star (asterisk)mark is the minimum height of the ejector pin.

In step U7, the ejector pin design section 66 may set the minimum heightof the ejector pin as the basis of guide length calculation. The guidelength may provide a shift distance (ejection stroke) when the moldingsis ejected. The maximum height of the ejector pin is a distance from thesurface of the lower ejector plate to the top end of the ejector pin.The minimum height of the ejector pin is varied in compliance with slantof the product surface. The ejector pin design section 66 may readdimension values of thicknesses of, for instance, core block 30, coreplate (not shown), support plate, upper ejector plate, etc. from thework memory 13, an then add these thicknesses. The maximum height of theejector pin may be derived from the result of this addition.

In step U8, the ejector pin design section 66 may form profiles of theejector pin and the hole based on ejector pin hole diameter, relief holediameter, guide length, rib diameter, and so forth designated by thedesigner.

In step U9, the designer may decided whether or not all ejector pinshave been designed. If all ejector pins have been designed (YES), thenthe process advances to step U10. Unless all ejector pins have beendesigned (NO), then the process returns to step U1 where dimensionsrequired for design are input. Then, following steps U2 to U9 areexecuted once again.

In step U10, the designer may determine whether or not designinformation of the ejector pin must be output. If design information ofthe ejector pin must be output (YES), then the process goes to step U11where design information is either displayed on the screen of thedisplay 19 or output on the paper by the printer 20. By way of example,in FIG. 70D, the example has been given wherein the result of design oftwo ejector pins are output on the paper. The output contents are suchas locations, hole diameters, relief hole diameters, guide lengths andejector pin lengths. In step U11, design of the ejector pin may be endedafter design information are output. Unless design information of theejector pin must be output in step U10 (NO), design of the ejector pinmay also be ended.

As has stated above, according to the design process of the ejector pinaccording to the twenty-fourth embodiment of the present invention, whenthe designer designates the location of the ejector pin on the screen ofthe display 19, the ejector pin design section 66 may detect locationsX, Y of the ejector pin from the center of the mold, and calculate theheight from the upper ejector plate. Thus, it would be understood that,although the mold has a complicate profile, the ejector pin may bedesigned in an interactive manner between the designer and the system.

(25) Twenty-Fifth Embodiment

FIG. 71 is a flowchart illustrating design process of mold base of themold according to the twenty-fifth embodiment of the present invention.FIG. 72 is a view for use in supplementary explanations. In thetwenty-fifth embodiment, entire profile of the mold base constitutingthe mold, and an instruction boxes in which dimensional values ofrespective constituent parts are input may be displayed in one screen.

In FIG. 71, in step V1, the designer may select kinds of the mold baseof the mold. At this time, the display 19 may display a menu screen, asshown in FIG. 72. The display contents are mold base formation,arrangement determination, dimension corection, mold base save, moldbase read, etc. If the designer selects “mold base formation”, thedisplay 19 may switch to the menu screen showing kinds of the mold base.The kinds of the mold base are SA type, SC type of two-plate structure,and DA type, DC type of three-plate structure. SA type and SC type arethe mold consisting of two-mold plates of the cavity plate and the coreplate. DA type and DC type are the mold consisting of three-mold platesof the cavity plate, the core plate and the runner stripper plate. TheSA type and DA type have the support plate, but the SC type and DA typehave not the support plate.

In step V2, the display 19 may display the instruction window in whichprofile of the mold base and dimensional values are input. In theexample in FIG. 73, entire profile of the SA type mold base andinstruction boxes X, Y, TW, CP, A, B, U, C, SP, EP, E1, and E2, in whichdimensional values of respective constituent parts being input, on onescreen of the display 19. In the example in FIG. 73, a reference {circlearound (1)} denotes a fixing side clamping plate; {circle around (2)},fixing side mold plate; {circle around (3)}, movable side mold plate;{circle around (4)}, support plate; {circle around (5)} and {circlearound (6)}, spacer blocks; {circle around (7)}, upper ejector plate;{circle around (8)}, lower ejector plate; and {circle around (9)},movable side clamping plate.

X is a lateral length of the fixing side mold plate {circle around (2)},the movable side mold plate {circle around (3)}, and the support plate{circle around (4)}. Y is a vertical length of the fixing side clampingplate {circle around (1)}. TW is a lateral length of the fixing sideclamping plate {circle around (1)}. CP is a height of the fixing sideclamping plate {circle around (1)}. A is a height of the fixing sidemold plate {circle around (2)}. B is a height of the movable side moldplate {circle around (3)}. U is a height of the support plate {circlearound (4)}. C is a height of the spacer blocks {circle around (5)} and{circle around (6)}. SP is a lateral length of the spacer blocks {circlearound (5)} and {circle around (6)}.

EP is a lateral length of the upper ejector plate {circle around (7)}and the lower ejector plate {circle around (8)}. E1 is a height of theupper ejector plate {circle around (7)}. E2 is a height of the lowerejector plate {circle around (8)}. A distance between E1 and E2 is 4 mm.

The designer may input dimentional values into these instruction boxesX, Y, TW, CP, A, B, U, C, SP, EP, E1, and E2 via the keyboard 17.

In step V3, the mold base forming section 61 may form mold base data incompliance with dimensional values input by the designer. Theexplanation of the method for forming the mold base data will be omittedsince it has been described in the twelfth embodiment.

As mentioned earlier, according to the twenty-fifth embodiment of thepresent invention, entire profile of the mold base constituting themold, and instruction boxes in which dimensional values of respectiveconstituent parts are input may be displayed in one screen. Therefore,it would be understood that, with confirming an expected complete shape,the designer may design the injection mold by inputting dimentionalvalues into these instruction boxes X, Y, TW, CP, A, B, U, C, SP, EP,E1, and E2, which thus facilitates the design of the mold.

(26) Twenty-Sixth Embodiment

FIG. 74 is a flowchart illustrating usage of the configuration file ofthe mold design system according to the twenty-sixth embodiment of thepresent invention. FIG. 75 is a view for use in supplementaryexplanations. In the twenty-sixth embodiment, usages of the tools forsupporting the mold design system may be disclosed. In FIG. 74, in stepW1, the designer may save the default value file in the system. Thisfile in which the tools for supporting the mold design system arewritten would be written into the memory 21 shown in FIG. 2.

In FIG. 75, the contents of the tool are designation of display color oflines, characters and regions, output method of design information,reference value (design data) required for each design, and notation ofrespective parts data. In the twenty-sixth embodiment, the product shapedata is displayed by “CYAN”, the undercut portion is displayed by“PINK”, the parting line is displayed by “YELLOW”, the cavity/core isdisplayed by “MAGENTA”, the mold base is displayed by “WHITE”, and theejector pin is displayed by “BLUE”. The display 19 may display lines,characters and regions based on such classification of color.

In the twenty-sixth embodiment, the undercut portion may be output tothe display 19 by “GRPHICS”, and the ejector pin and the manufacturingjigs of the mold parts may be output to the printer 20 by “PAPER”.

In addition, in the twenty-sixth embodiment, as for an approachallowable distance (hole interference check distance) between theejector pin hole and other holes, 3 mm may be registered as an isolationstandard value. As for an extrusion stroke a to the length of theejector pin, 0.1 mm may be registered as an isolation standard value. Asfor an extrusion stroke to the manufacturing jigs of the mold parts, 10mm may be registered as an isolation standard value. As for an offsetamount of the base of the manufacturing jigs, 10 mm may be registered asan isolation standard value.

With respect to ejector pin design, parts data concerning the core blockmay be displayed by “CORE-BLOCK”, parts data concerning the core platemay be displayed by “CORE-PLATE”, parts data concerning the upperejector pin may be displayed by “EPR”, and parts data concerning thelower ejector pin may be displayed by “EP”.

With respect to cooling water path design and nest design, parts dataconcerning the cavity plate may be displayed by “CAVITY-PLATE”, partsdata concerning the cavity block may be displayed by “CAVITY-BLOCK”,parts data concerning the core plate may be displayed by “CORE-PLATE”,and parts data concerning the core block may be displayed by“CORE-BLOCK”.

Next, in step W2, the designer may decide whether or not the defaultvalue must be varied. If the default value must be varied (YES), then instep W3 the default value is varied. The designer may vary the defaultvalue by rewriting the contents of the configuration file. Thus,designation of display color of lines, characters and regions, outputmethod of design information, reference value (design data) required foreach design, and notation of respective parts data can be varied freely.

Unless the default value must be varied in step W2 (NO), then in step W4the system is started. In response to starting of the system, thedisplay 19 may display the product shape by “CYAN” in compliance withthe configuration file.

In step W5, if the designer designates the information output method“GRPHICS” to detect the undercut portion, the display 19 may display theundercut portion in compliance with the configuration file.

In step W6, in order to form the parting, the display 19 may display thecolor of the parting by “YELLOW” in compliance with the configurationfile.

In step W7, in order to form the mold base and the cavity/core, thedisplay 19 may display the color of the mold base by “WHITE” and thecolor of the cavity/core by “MAGENTA” in compliance with theconfiguration file.

In step W8, when checking interference between holes, the ejector pindesign section 66 may execute check process of interference between pinhole and other holes depending upon the standard value=3 mm read fromthe comfiguration file.

In step W9, when designing the ejector pin, the ejector pin designsection 66 may add the extrusion stroke α=0.1 mm being read from theconfiguration file to a maximum height of the ejector pin.

Further, in step W10, when designing the electric discharge machiningelectrodes, the designer may design the electric discharge machiningelectrodes (manufacturing jigs of the mold parts) based on the extrusionstroke=10 mm being read from the configuration file. The designer mayalso design the base of the electrodes based on the offset amount beingread from the configuration file.

Like the above, according to usage of the configuration file of the molddesign system of the twenty-sixth embodiment of the present invention,it should be noted that, although a plenty of automatic processing arebeing employed, display color of lines, characters and regions, outputmethod of design information, reference value (design data) required foreach design, and notation of respective parts data can be variedarbitrary in step W3. Therefore, the mold design system which is fittedto each designer can be built up. Furthermore, the input items needed indesigning process can be reduced by preparing the configuration file inadvance.

(27) Twenty-Seventh Embodiment

FIG. 76 is a flowchart illustrating design process of the mold accordingto the twenty-seventh embodiment of the present invention. FIG. 77 is aview for use in supplementary explanations, i.e., a perspective viewshowing an injection mold device when individual attributes are allottedto names of respective parts of the device. In the twenty-seventhembodiment, in order to improve operability of the mold design system,first names (attributes) are assigned to data groups for designing themold, and then nest type mold or direct impression type mold may bedesigned based on these attributes.

In FIG. 76, in step X1, the designer may first assign a name (attribute)of “PART” to product shape data at starting the design system. If thereare a plurality of data groups, the designer may select and assignanother name.

For instance, in step X2, when forming the parting line, the designermay assign a name of “PARTING-LINE” to a data group of the parting line.

In step X3, when correcting shrinkage rate, the designer may select adata group of “PART” and “PARTING-LINE”. In that case, the product shapecorrection editor 14 may read out a data group of “PART” and“PARTING-LINE” from the memory 11 and the memory 13 and, as hasexplained in the third embodiment, then automatically correct theproduct shape.

In step X4, when designing the cavity and the core, the designer mayassign a name of “CAVITY/CORE-BLOCK” to a data group of cavity/core. Inthe case that the nest type mold is designed, there exists a data groupconcerning the cavity/core block.

In turn, in step X5, when designing the mold base, the designer mayassign names of “TCP”, “CAVITY-PLATE”, “CORE-PLATE”, “SP”, “SB”, “EPR”,“EP” and “BCP” to groups of the mold base data. In FIG. 77, a reference31 denotes fixing side clamping plate which is displayed as “TCP” in thesystem; 32, fixing side mold plate being displayed as “CAVITY-PLATE”;33, movable side mold plate being displayed as “CORE-PLATE”; 34, supportplate being displayed as “SP”; 35, spacer block being displayed as “SB”;36, upper ejector plate being displayed as “EPR”; 37, lower ejectorplate being displayed as “EP”; 38, movable side clamping plate beingdisplayed as “BCP”; 39, fixing side block being displayed as“CAVITY-BLOCK”; 40, movable side block being displayed as “CORE-BLOCK”.

In the event that the direct impression type mold is designed, thereexists data groups as to the cavity plate and the core plate. The moldbase design section 61 may read out data groups of “TCP”,“CAVITY-PLATE”, “CORE-PLATE”, “SP”, “SB”, “EPR”, “EP” and “BCP” from thememory 12 and, as has discussed in the twelfth and twenty-fifthembodiments, then form the mold base.

In step X6, when forming the parting plane, the cavity design editor 15may form the parting plane on the basis of data group of the name“PARTING-LINE”. The designer may assign a name of “PARTING-SURFACE” to adata group of the formed parting plane.

Subsequently, in step X7, the designer may detect whether or not thereis the data group having the name of “CAVITY/CORE-BLOCK”. If“CAVITY/CORE-BLOCK” has been detected (YES), then the process advancesto step X8 since this corresponds to design of the nest type mold.

In step X8, the cavity design editor 15 may form a cavity portion of“PART” in “CAVITY/CORE-BLOCK”. Here the cavity design editor 15 may readout the data groups concerning “CAVITY/CORE-BLOCK” and “PART” from thework memory 13 and, as has discussed in the ninth and twenty-thirdembodiments, then execute data processing.

In the next, in step X9, the cavity design editor 15 may split the moldblock into two parts in “PARTING-SURFACE”. The cavity design editor 15may read out the data group of “CAVITY/CORE-BLOCK” from the work memory13 and, as has described in the tenth embodiment, then split the moldblock into the cavity and the core based on the parting plane. Two splitportions are referred to as “CAVITY-BLOCK” and “CORE-BLOCK”. The“CAVITY-BLOCK” may serve as the fixing side block and the “CORE-BLOCK”may serve as the movable side block.

On the other hand, there has been no data group as to“CAVITY/CORE-BLOCK” in step X7 (NO), then the process advances to stepX10 since this corresponds to design of the direct impression type mold.In step X70, the designer may combine data groups of “CAVITY PLATE” and“CORE PLATE” with each other into a data group, and then assign a nameof “CAVITY/CORE-PLATE” to the data group. To combine two data groupsinto one group means the fact that two plates are stacked.

In turn, in step X11, the cavity design editor 15 may form a cavityportion of “PART” in “CAVITY/CORE-PLATE”. Then in step X12, the cavitydesign editor 15 may split the mold block into two parts in“PARTING-SURFACE”. Two split portions are referred to as “CAVITY-PLATE”and “CORE-PLATE”. The “CAVITY-PLATE” may serve as the fixing side moldplate and the “CORE-PLATE” may serve as the movable side mold plate.

In addition, in step X13, when designing the cooling water path, thedisplay 19 may read data groups relating to “CAVITY-BLOCK” or“CAVITY-PLATE” and “CORE-BLOCK” or “CORE-PLATE” from the work memory 13,and then display the fixing side block or the fixing side mold plate andthe movable side mold block or the core side mold plate on the screen ofthe display 19.

In step X14, when designing the ejector pin, the display 19 may readdata groups as for “CORE-BLOCK”, “CORE-PLATE”, “EPR” and “EP” from thework memory 13, and then display the core block, the core side moldplate, the support plate, and the ejector plate on the screen of thedisplay 19.

If the location of the ejector pin has been decided by the designerhere, the ejector pin design section 66 may form pin holes through fourrelated parts, i.e., core block, core side mold plate, support plate,and upper ejector plate. In order to form the pin holes so as topenetrate four related parts collectively, consistent coordinate systemsof data groups concerning “CORE-BLOCK”, “CORE-PLATE”, “EPR” and “EP” areneeded. If the consistent coordinate systems have been achieved,profiles enabling the holes to be formed in these four related partssimultane-ously may be designed on the same position as that of thedesignated ejector pin.

In this manner, according to the twenty-seventh embodiment of thepresent invention, it would be evident that, since names (attributes)have been assigned to data groups of the product and the mold parts,only data groups required for in the course of respective design stagesmay be selected. Therefore, since data groups being obstructive to thedesign operation has been unloaded into the memory, design operation canbe simplified.

Moreover, according to the twenty-seventh embodiment of the presentinvention, it would be understood that, although four related parts intowhich the pin holes must be formed are needed, this operation may beeffected together in the ejector pin design section 66 by assigning theattributes for unifying the coordinate system of the data groupsconcerning core bock, core side mold plate, support plate, and ejectorplate.

(28) Twenty-Eighth Embodiment

FIG. 78 is a flowchart illustrating design process of hole portions inthe mold parts according to the twenty-eighth embodiment of the presentinvention. FIGS. 79A to 79C are views for use in supplementaryexplanations, i.e., perspective views showing interference between thecooling water path and the ejector pin holes. In the twenty-eighthembodiment, there is disclosed a method for designing the ejector pinholes and holes for the cooling water paths, etc. not to overlap witheach other. In FIG. 78, in step Y1, the designer may first storeinformation as to all holes of the mold parts in the design system.Tapped holes and guide holes for fixing the mold parts, cooling waterpaths for adjusting the temperature of the mold, ejector pin holes forejecting the product from the mold, etc. are intended for the injectionmold. These data may be stored in the design data memory 11.

In step Y2, the designer may select design items relating to holeformation of the mold. As has been explained in the twentiethembodiment, the design items are, for example, correction of moldingshrinkage rate, formation of cavity/core block, determination of moldbase, formation of the parting plane, design of gate, runner and sprue,design of mold temperature adjusting water path, design of ejector pin,check of hole interference, split of nest structure, and design of slidecore. For example, as shown in FIG. 79A, the designer may select designof the mold temperature adjusting water path to design the cooling waterpath 44 in the fixing side mold plate 32.

Next, in step Y3, the designer may design a certain hole profile in theselected design items. Then, as has explained in the seventeenthembodiment, the designer may design the cooling water path.

In step Y4, the ejector pin design section 66 may detect whether or nota hole to be designed (referred to as “design hole” hereinafter)interferes with other holes. For instance, the design hole is thecooling water path 44 whereas, as shown in FIG. 79B, an objective ofother holes is an ejector pin hole 45 which penetrate movable side block40, fixing side mold plate 32, and upper ejector plate 33 together. Asshown in FIG. 79C, based on that the distance between the location ofthe cooling water path 44 and the location of the ejector pin hole 45can be kept more than a standard value, it may be determined whether ornot the cooling water path 44 does interfere with the ejector pin hole45. An isolation standard value=3 mm, which having been discussed in thetwenty-sixth embodiment, may be used as the foregoing standard value.This standard value may be stored in the configuration file.

Unless the interference between the cooling water path 44 and theejector pin hole 45 has been caused in step Y4 (NO), then in step Y5hole profile data of the cooling water path 44 are stored. On thecontrary, if the interference between the cooling water path 44 and theejector pin hole 45 has been caused in step Y4 (YES), then in step Y6interference portion of the hole may be depicted on the display 19, asshown in FIG. 79C. Then this hole profile data may be removed.

In step Y7, the designer may determined whether or not design operationof entire holes have been completed. If the entire holes have beendesigned (YES), then the process goes to step Y8. Unless the entireholes have been designed (NO), then the process returns to step Y3 wherethe design operation of the hole profile may be continued. If all holeshave been designed, then in step Y8 the designer may determine whetheror not the design items must be changed. If the design items have beenchanged (YES), then the process proceeds to step Y2 where the designitem may be selected. While, unless the design items have been changed(NO), then the hole design operation is terminated.

In this fashion, according to the hole design method of the mold of thetwenty-eighth embodiment, it should be noted that, since interferencebetween holes in design and other holes has been checked in step Y4,design errors such as overlapping of the cooling water path 44 and theejector pin hole 45, for example, can be prevented.

(29) Twenty-Ninth Embodiment

FIG. 80 is a flowchart illustrating design process of the manufacturingjigs of the mold parts according to the twenty-ninth embodiment of thepresent invention. FIGS. 81A to 81F are views for use in supplementaryexplanations. In the twenty-ninth embodiment, the case may beparticularly shown wherein electrodes (manufacturing jigs) fordischarge-working the corners inside of the cavity block in an R-likeshape should be designed. In FIG. 80, in step Z1, the designer may firstselect concerned mold parts. For instance, in case the corner portionsof the product shape 46 would be finished to have an R shape, as shownin FIG. 81A, the inner corners of the cavity block must be worked inadvance in an R-like shape. To this effect, the designer may select thecavity block 39, as shown in FIG. 81B. The display 19 may display thecavity block 39 designated by the designer. The profile data of othermold parts have been unloaded into the memory.

In step Z2, the designer may designate a range of the manufacturing jigsto the mold parts being displayed on the display 19. The range may bedesignated via the keyboard 17. In FIG. 81B, the range of themanufacturing jigs are the region for connecting both ends of theconcave portion of the cavity block 39. The width of the manufacturingjigs may freely decided by the designer.

Subsequently, in step Z3, the designer may form an extrusion profile 47Ahaving the range as the sectional shape. In FIG. 81, the extrusionprofile 47A may comprise a portion extending from the back side of thissectional shape to the bottom of the cavity block 39 and a portionextruded from the front side of the sectional shape by a predetermineddistance. Since this predetermined distance has been stored in theconfiguration file as an extrusion amount, it can be used by readingfrom the file. In the twenty-ninth embodiment, the predetermineddistance=10 mm is set as a standard value.

Thereafter, in step Z4, the concave shape of the cavity block (moldprofile) 39 may be transferred to the extrusion profile 47A. In otherwords, the sectional shape of the extrusion profile 47A is projectedonto the concave portion of the cavity block 39 to transfer R shape,side shape, and bottom shape of the corners. Transfer process mayexecute by subtracting unnecessary profile portions from the solidprofile formed by projection of the sectional shape in terms of Booleanoperation. Thereby, as shown in FIG. 81D, an electric dischargemachining electrodes 47 may be designed.

In step Z5, a reference location from the center of the injection moldis designated on the electrode 47. In the twenty-ninth embodiment, forinstance, the reference location may be designated like (−200, 350). Thedesignation of the reference location has to be designated to executeelectric discharge machining the concave portion of the cavity plateexactly.

Next, in step Z6, a base 48 may be formed on the electrode 47. The base48 may be formed by adding an offset amount, as shown in FIG. 81E, todimension of the bottom surface of the electrode 47. The offset amountmay be read from the configuration file. In the twenty-ninth embodiment,a reference value is 10 mm. A thickness of the base may be determinedarbitrarily by the designer. Consequently, the electrodes (manufacturingjigs) 47 for electric-discharge machining the inner corners of thecavity block 39 to have an R-like shape have been designed. Profile dataof the electrode 47 may be converted into numerical control data.

After this, in step Z7, the designer may determine whether or notinformation of the electrode 47 are output. If information of theelectrode 47 have been output (YES), then in step Z8 the display 19 mayoutput the profile of the electrode 47 on the screen according toinstruction of the designer. The printer 20 may also output informationof the concerned parts on the paper according to instruction of thedesigner. Output information corresponds to the mold parts being workedby the electrode 47. In the example shown in FIG. 81F, the case has beenillustrated wherein the concerned parts name is “CAVITY-PLATE”, thereference location of the electrode 47 from the center of the mold is(−200, 350), the profile of worked material is X=80, Y=90, and Z=40.Output information of the concerned parts may be offered to the moldmanufacturer.

On the contrary, unless information of the manufacturing jigs haveoutput in step Z7 (NO), then in step Z9 the designer may determinewhether or not other manufacturing jigs should be designed. If othermanufacturing jigs have been designed (YES), then the process returns tostep Z1 where the mold parts may be selected. Subsequently, steps Z2 toZ8 may be repeated.

As has been stated earlier, according to the design method for themanufacturing jigs of the mold parts of the twenty-ninth embodiment ofthe present invention, it would be evident that, since the designer maydesignate the range of the manufacturing jigs for the cavity block 39 instep Z2 and the system may form the extrusion profile 47A having therange as the sectional shape in step Z3, the designer may design theelectric discharge machining electrode 47 in a manner interacting withthe system.

In addition, according to the twenty-ninth embodiment, it would beapparent that, since the reference location from the center of theinjection mold may be designated on the electrode 47 in step Z5,electric discharge machining operation of the concave portion of thecavity plate can be performed exactly by placing the electrode 47 on thereference location.

What is claimed:
 1. An injection mold design method for correcting aprofile of a product to be fabricated into a releasable profile from amold comprising: (a) calculating a normal vector on a plane of a productshape and a reference vector in a mold opening direction; (b) detectinga normal vector having the opposite direction to that of the referencevector so as to detect undercut portion; and (c) after the step (b),forming a split borderline for a slide structure of the mold.
 2. Aninjection mold design method as claimed in claim 1, further comprising:(d) after the step (c), editing a main split borderline that splits amold block into a cavity a core.
 3. An injection mold design method asclaimed in claim 2, further comprising: (e) after the step (d),executing a loop check for the main split borderline to check whetherthe main split borderline is closed or not; and (f) if the main splitborderline is checked as being not closed in the step (e), repeating thesteps (c) to (e) until the main split borderline closes.
 4. An injectionmold design method as claimed in claim 2, wherein the step (d) furthercomprises: (d i) removing temporarily part of lines or planesconstituting a product shape or a mold profile from a screen; and (d ii)replotting the lines of planes on the screen after the editing operationof the main split borderline is completed.
 5. An injection mold designmethod for correcting a profile of a product to be fabricated into areleasable profile from a mold comprising: (a) designating a planeelement of the product; (b) calculating a shrinkage vector of a resinwhose surface defines the plane element where the vector is defined whenthe resin shrinks; (c) multiplying a norm of the shrinkage vector and anarea of the plane element together to obtain a shrinkage force; (d)calculating a sticking strength of the product to the mold bymultiplying the shrinkage force and a certain coefficient; and (e)judging whether an ejector force of an ejector pin is greater than thesticking strength of the product.
 6. An injection mold design method asclaimed in claim 5, further comprising (f) correcting the product shapeif the ejector force of the ejector pin is judged as being not greaterthan the sticking strength of the product in the step (e); and (g)repeating the steps (a) to (f) until the ejector force of the ejectorpin becomes greater than the sticking strength of the product.
 7. Aninjection mold design method as claimed in claim 6, wherein the step (f)further comprises: (f i) removing temporarily part of lines or planesconstituting the product share or a mold profile from a screen; and (fii) replotting the lines or planes on the screen after the correctionoperation is completed.
 8. An injection mold design method according toclaim 5 further comprising (f) calculating a total shrinkage force of acore surface of the product based on the sticking strength of theproduct; (g) calculating a total shrinkage force of a cavity surface ofthe product based on the sticking strength of the product; (h) judgingwhether the total shrinkage force of the core surface is greater thanthe total shrinkage force of the cavity surface; (i) correcting aproduct shape if the total shrinkage force of the core surface is judgedas being not greater than the total shrinkage force of the cavitysurface in the step; and (j) repeating the steps (a) to (e) and (f) to(i) until the total shrinkage force of the core surface becomes greaterthan that of the cavity surface.
 9. An injection mold design method asclaimed in claim 5, further comprising: (f) calculating a normal vectoron a plane of a product shape and a reference vector in a mold openingdirection; and (g) detecting a normal vector having an oppositedirection to that of the reference vector so as to detect undercutportion.
 10. An injection mold design method as claimed in claim 1,further comprising the step of: (d) calculating a degree of deformationof a product based on a shrinkage rate of a resin that constitutes theproduct.
 11. An injection mold design method as claimed in claim 10,further comprising the step of: (e) judging whether the product isreleasable from the mold based on the calculated degree of deformation;(f) correcting a product shape if the product is judged as being notreleasable from the mold in the step (e); and (g) repeating the steps(d) to (f) until the product becomes releasable from the mold.
 12. Aninjection mold design method as claimed in claim 11, wherein the step(f) further comprises: (f i) removing temporarily part of lines orplanes constituting a product shape or a mold profile from a screen; and(f ii) replotting the lines of planes on the screen after the correctionoperation is completed.
 13. An injection mold design method comprising:(a) forming a mold block; (b) reading a product shape data; (c)displaying the mold block and the product so as to overlap each other ona screen; and (d) judging whether a size and a profile of the mold blockis suitable to the product shape.
 14. An ejection mold design method asclaimed in claim 13, further comprising: (e) modifying a dimension ofthe mold block if the size and the profile of the mold block is judgedas being not suitable to the product shape in the step (d).
 15. Aninjection mold design method as claimed in claim 13, further comprising:(e) after the step (d), making a portion in the mold block hollow wherethe portion corresponds to the product shape.
 16. An injection molddesign method for correcting a profile of a product to be fabricatedinto a releasable profile from a mold comprising: (a) forming a splitplane by extending a designated split borderline in parallel to adesignated direction when a mold block is split into a core and cavity;and (b) forming a split borderline for a slide structure of the moldblock after the step (a).
 17. An injection mold design method as claimedin claim 16, further comprising: (c) forming a slide split plane basedon the split borderline for the slide structure.
 18. An injection molddesign method as claimed in claim 17, further comprising: (d) dividingthe mold block into the core and the cavity based on the slide splitplane.
 19. An injection mold design method as claimed in claim 18,further comprising: (e) judging whether the mold block can be opened ornot by checking whether there exists interference between the core andthe cavity or not.
 20. An injection mold design method as claimed inclaim 19, further comprising: (f) repeating the steps (a) to (e) untilthe interference between the core and the cavity disappears if the moldblock is judged as being not opened.